Will using higher RON or Super Unleaded fuel help my car?

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Will using higher RON or Super Unleaded fuel help my car?

Post by James Curgenven » Sat Aug 16, 2008 4:55 pm

This comes up so often I thought I'd write a short summary and then quote Deb's posts on the subject and make it a sticky post at the top.

Oh, and if you don't want to read it all the answer is "no, using higher octane fuel won't make your F or TF go faster", but the extra cleaning additives in such as Shell's V Power will help keep your engine clean, which will help good lasting performance. So while running an F on V Power constantly will just drain your wallet, putting a tank full in occasionally will help keep it in good running order.

Now, onto the technical goddess' post :)
Debs wrote:Can an F/TF take advantage of 97 Octane (RON), or higher, fuel as stock?


The simple answer is no! because the engine management system is mapped for 95 RON (in fact it’s mapped for slightly worse, giving a level of 'belts 'n braces' protection against detonation [pinking]). While there may be some advantages from using 97 RON or 99 RON fuels, these accrue from the fact that:

1. Higher Octane fuels tend to contain a better detergent package. These are said to keeps the engine internals cleaner and, therefore, more efficient. Ie frictional losses are reduced. This also helps prevent pre-ignition (qv later) by keeping the cylinders clear of unburnt carbon deposits.

2. Higher Octane fuels contain a slightly higher amount of Iso-Octanes (8-Carbon chain molecules) and should (theoretically) produce more combustion product leading to greater power. This is (at best) likely to be in the region of only 1 or 2 bhp and would not be felt by the driver.



Whether a knock sensor is fitted is irrelevant and is a myth that gets posted around on a regular basis. A knock sensor senses knock (detonation) and signals the ECU to retard the ignition during periods of detonation (such as when running on too low an Octane fuel). When the detonation stops the ECU will advance the ignition back to factory setting. The system will not advance past its mapped setting. Thus if you are mapped for 95RON you cannot take advantage of higher octane fuels whether you have a knock sensor or not.



To understand why this is the case we need to understand what is going on in the cylinder, why we use ignition advance, what detonation is, and what high octane fuels provide.



A 4-stroke or ‘Otto Cycle’ engine goes through four distinct 'strokes' as the pistons move up and down the bores. Simplistically it is as follows:

1. Induction Stroke: The Inlet valve opens, the piston moves down the bore causing a vacuum and sucking in the Fuel/Air charge.

2. Compression Stroke: The Inlet and Exhaust valves are closed, the piston moves up the bore thereby compressing the Fuel/Air charge.

3. Power Stroke: The Inlet and Exhaust valves are closed, the spark plug fires, the Fuel/Air charge is burnt producing expanding gasses that push the piston down the bore.

4. Exhaust Stroke. The Exhaust valve is open, the piston moves up the bore forcing the burnt Fuel/Air charge out through the Exhaust Valve.


Therefore the output (Torque) of any given 4-Stroke motor is directly proportional to the pressure exerted by the expanding gasses, produced by the burning Fuel/Air charge, upon the piston pushing it down the bore and, hence, causing the crankshaft to rotate.


Now, ideally, you want the expanding combustion gasses to start pushing upon the piston when it is at TDC. If they start pushing when the piston is still coming up the bore on the Compression Stroke (ie BTDC) then they will be fighting against the piston resulting in a reduction in torque output (and, hence, a drop in power). If they start pushing when the piston is already going down the bore on the Power Stroke (ie ATDC), then, again, there will be a loss in torque (and hence power) because they are pushing into a space that is expanding so the pressure felt by the piston will be less.

In an ideal world, therefore, you would have the spark plug fire giving an instantaneous ignition of the Fuel/Air charge at TDC, with an instantaneous burn, and a concomitant instantaneous expansion of the combustion gasses.

Of course, we don’t inhabit such an ideal world and it takes finite amounts of time for the spark plug to fire, for the flame front to expand across the piston face, for the charge to fully burn, and for the combustion gasses to exert pressure on the piston.

Therefore we fire the spark plug before TDC such that the burnt charge exerts its maximum pressure on the piston at TDC (in reality this maximum pressure usually occurs slightly after TDC for a number of reasons, not least detonation. (qv later). This is known as Ignition Advance.


As engine speed increases (ie rpm's rise) there is less time per cycle for these processes to occur so, for maximum performance, you require increasing amounts of Ignition Advance. This is known as an Ignition Advance Curve and is controlled by the distributor (early cars) or the ECU (later cars).

In fact distributors give a fixed (mechanical) advance curve, ie they are 2D and map purely Ignition Advance versus rpm, whereas an ECU controlled system can be mapped to give variations in the curve at different rpm's to take account of such things as changes in cylinder burn rates caused by differing engine loads (they will assess Throttle Position and/or Manifold Air Pressure), ie they are 3D. In fact the ECU can also alter the fuelling, thereby giving a more efficient burn throughout the rpm range than can be achieved by a distributor/carburettor set up.




OK so what is Detonation?


To understand this we have to take account of a piece of Physics known as 'Boyle's Law'. This states, for any compressible fluid such as the Fuel/Air charge in an engine, that:

[Pressure x Volume] / Temperature = Constant

That is to say that if you have a fixed volume of gas (the Fuel/Air charge), if you compress it, it will heat up.

So, on the Compression Stroke, what we are doing (aside from the heat soak from a hot motor) is heating the Fuel/Air charge as it is squeezed by the rising piston.

Now, obviously, the Fuel/Air charge has got fuel in it (petrol) so there will come a point whereby the compression induced heating effect will cause the charge to self ignite (in fact this is how diesels work – they don’t have spark plugs, but rely upon compression to ignite the Fuel/Air charge).

In cases of detonation, what happens is the spark plug fires (as we said, BTDC) and the flame front starts to travel across the piston face. If then the fuel also self ignites we have two flame fronts that must eventually collide. Now, while I said it takes a finite amount of time for a flame front to travel, the fact is that it is travelling at supersonic speed. So, when the two flame fronts collide, they do so with massive force, resulting in a sudden huge pressure 'spike'. Owing to Boyle's Law this pressure spike causes an enormous temperature spike sufficient to burn through to the piston face / cylinder head face causing pitting, or (at worst) a hole in the piston crown. On an engine such as the K Series, pitting of the cylinder head face renders it scrap.

(Note. There is another effect known as pre-ignition whereby something glowing red hot in the cylinder, such as a spark plug that is of too soft (hot) a grade for the motor or an incandescent carbon deposit ignites the Fuel/Air charge before the spark plug fires. The effect is the same – two (or more) flame fronts colliding.)



So, what puts your motor at risk of detonation?

1. Running too much Ignition Advance. If we ignite the Fuel/Air charge too early on the Compression Stroke then the charge will start burning before the piston reaches TDC. If this happens the expanding gasses are fighting against the rising piston causing increased cylinder pressure (ie more heating) to the point where detonation is likely to occur.

2. Too high a Dynamic Compression Ratio for the fuel being used. Static Compression Ratio (CR) is the ratio between the cylinder swept volume and the volume of the combustion chamber. For the F/TF this is 10.5 : 1. However Static Compression Ratio takes no account of the fact that the valves are open during much of the engine's cycle. On racing engines with long duration (ie the valves are open longer), wide overlap (ie both the Inlet and Exhaust valves are open together) camshafts, the Dynamic Compression Ratio is far lower than the Static Compression Ratio so overall higher Static ratios are used as well as greater amounts of Ignition advance. For example our racing Midget uses 11.75 : 1 Static with 29 degrees advance BTDC at 3000 rpm. However, the higher the Compression Ratio the closer you get to the detonation line.

3. Too lean a Fuel/Air charge. Leaning out the mixture causes it to burn hotter and faster. On the other hand running a slightly rich mixture will mean that not all the fuel is burnt and the unburnt fuel can act as a 'heat sink' absorbing the heat and carrying it away through the Exhaust Valve (this is why Nitrous motors are set up to over-fuel slightly to keep them safe from detonation). However, too rich a mixture will result in a drop in power, cylinder bore wear owing to the petrol removing the oil film, increased emissions and, ultimately, catalyst failure.

4. Running an engine too hot, causing excessive heat soak into the Fuel/Air charge.



So how do we prevent detonation?

1. Don’t run too much Ignition Advance. This is where Knock Sensors are helpful since they signal the ECU to retard the Ignition if detonation starts to occur.

2. Don’t run lean.

3. Don’t run hot.

4. Use a fuel that is detonation resistant.




Detonation resistance in petrol is indicated by its RON. The higher the octane, the more detonation resistant it is. In the old days of leaded fuel, Tetra-Ethyl Lead was added to prevent the fuel detonating (as well as to protect the Exhaust Valve seats). However, Lead is a toxin.

Once Unleaded fuels became the norm, initially benzo-phenolic compounds were added (although these were highly carcinogenic). Other additives included Methylcyclopentadienyl manganese tricarbonyl (MMT) (a powerful neuro-toxin) and Methyl tertiary-butyl ether (MTBE) which pollutes ground water supplies.

These days the trend is to add Ethanol (albeit at levels over 5% this can exacerbate fuel evaporation) and Ethyl tertiary-butyl ether (ETBE).



Higher RON fuels allow the use of increased Compression Ratio (CR) (we can’t change the CR of the K Series motor without a rebuild) and/or greater Ignition Advance (again we can’t change this on the K Series unless we re-map the ECU).




In conclusion then, the use of higher octane fuels is pointless in an F/TF (aside from the better detergent packages) unless the engine is rebuilt to a higher CR and/or the ECU is re-mapped to give increased Ignition Advance.
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Re: Will using higher RON or Super Unleaded fuel help my car?

Post by supasoaker » Fri Nov 14, 2008 12:24 pm

please excuse me for asking a dumb question but surely a modification of the spark timing also changes the compression ratio as the fuel/air mixture has more or less time to compress before being ignited...........................?

when you refer to the compression ratio are you referring to the physical dimensions of the internal cylinder volume i.e. - in regards to a k-series you need to manufacture a bigger bore/longer or shorter piston arm to accommodate for the extra power found in higher octane fuels?

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Re: Will using higher RON or Super Unleaded fuel help my car?

Post by Reckless Rat » Fri Nov 14, 2008 2:17 pm

Not exactly. Compression ratio is fixed and is independant of ignition timing. It is a ratio of the volume in the cylinder at Top Dead Centre to the Cylinder volume at Bottom Dead Centre . It can be altered by changing bore & stroke dimensions and also by altering cylinder head design. Low octane fuels used in high compression engines can cause pre-ignition, or knocking. This can be alleviated by retarding the ignition, but this affects power output. High octane fuels enable an engine to operate at higher compression ratios without suffering this phenomenon. However, as previously explained there is no benefit gained by using high octane fuel in an engine which is designed to run on low octane unleaded.

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Re: Will using higher RON or Super Unleaded fuel help my car?

Post by SkyJagMG » Fri Sep 11, 2009 10:03 am

I don't know anything technical about it but all i know is this...
when i buy a car i always drain out the tank fairly low of old petrol and fill it to the brim with 99RON, then fill up with the normal petrol as sticking with the 99 made no difference in performance after the first tank

I guess it helps clean the injectors a bit more or something like that but its worked well on the last 3 cars i've bought. I found the cars ran smoother and had better throttle response.

well worth the extra £3 a tank to fill it as a one off :thumbsu: its probablly worth doing every 6mths or so also

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Re: Will using higher RON or Super Unleaded fuel help my car?

Post by allun68 » Wed Nov 11, 2009 11:58 am

There may not be a technical advantage (ignition needs advancing to gain any extra power etc. etc...) but having tried it myself I found the car (MGF VVC with 76k on the clock and two HGF behind it), ran smoother and pick up was crisper. This maybe down to any detergents that may be present, I don't know, but I also noticed it ran slightly cooler which is never a bad thing on a midmounted K-series. I haven't noticed any differance on my new TF160 (27k) though.

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by mgf mark » Mon Oct 25, 2010 1:37 pm

hi
i used to fill up at asda till my f started playing up so i now use super plus car now sorted with new lamba ect, so filled up at asda again (new delivery of fuel) and car played up rough tick over
so i filled up again with super plus car runs like a dream
in my bike i only used shell petrol and thats always behaved after 8 years of track abuse

i dont mind paying a bit extra for the car to run and sound better it all down to choice
it will not cause any damage

mark

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by adrianclifford » Mon Oct 25, 2010 3:04 pm

Mark, this has been raised many times so it's no problem writing about it again as it's a very valued topic. My engine management light came on recently after filling up in my regular Aral station in Luxembourg (regular when I'm there that is as it's just before the Belgian border on the main road to Bastogne and Dunkerque and the tax is much lower). I had the car checked over in my local and trusted MG specialist garage and nothing wrong was found, the fault was cleared and away we went. Shortly after, the light came on again, still no problems with the car but it felt sluggish so the question was asked about fuel. The fault was cleared again and injector cleaner was put in the tank and it was filled with Shell V Power (which I try to use all of the time now), since that day and some 7,000 miles later there has been no repeat. If I'm abroad and can't find Shell, I'll use BP Ultimate or Aral Super but never ever supermarket brand fuel. I work in a fuel station for a main car dealership and the complaints I hear almost daily about cars playing up with Tesco/Asda/Sainsbury's fuel tells me I've done the right thing. If you don't use super, sure it's a little more but the engine runs better and I get more mpg, at least use good well known brand fuel.

You wouldn't use cheap tyres, brakes or servicing would you ? So look after your engine, it will love you for it :D
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Re: Will using higher RON or Super Unleaded fuel help my car

Post by dparker » Mon May 09, 2011 7:39 am

Fantastic explanation.
So from my understanding, it is prob best to stick with the bog standard fuel save from Shell (not the V power) as it has a fair amount of quality detergents but is standard fare as far as Ron is concerned.
(plus, near me it is the same price as Sainsbury's and Asda0

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by MartinW » Mon May 09, 2011 5:16 pm

Just a point of contention to add on this topic.

Any power gain is likely to be unnoticeable except as maybe a slightly crisper response. I quote Roger Parker who says that at least 10bhp power gain is required to be felt in reality. Hence any use of 99 vs. 95 is debatable and often subject to the emotive desire to want it to feel better or not. In addition it also depends on how we drive our cars, for example, many Rover 75 owners reckon Shell Vpower is a waste of time, yet many MG ZT owners with the similar KV6 engine swear by it, the latter owners being mopre likely to exceed 4000rpm in their normal driving.

All of that said, and accepting the excellent discourse above by Debs who certainly knows her stuff on engine theory as I recall from her posts in the MGOC BBS, I still use Vpower 99 in my MG TF and prior to that in my ZT 160 V6. The ZT benefited with knock sensors and I could certainly notice the loss of sparkle after a tankful of 95. However, on the TF, apart from the benefits of superior fuel quality as mentioned by Adrian, I am friendly with a chemist at Shell who assures me that the higher octane fuel is more dense and therefore there should be a gain in fuel economy. It can be argued that the gain is less than the greater cost of 99, but then again, I am willing to pay that little extra, as I am with oil, to ensure long term reliability of my engine, and to maintain it at peak performance with better oils and fuels.

Edit: Just to state that I have had my TF remapped for Vpower 99 to get the full benefit.
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Re: Will using higher RON or Super Unleaded fuel help my car

Post by michaelcngm » Fri Sep 16, 2011 4:55 pm

Also, now that fuel's so b****y expensive, it's only about 5% more to buy V-power or the like compared to regular 95 - probably about £20 more for 2000 miles in a year on your £350-odd fuel bill. Not bad value for an engine treat.

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by Flightline » Mon Jan 02, 2012 2:56 am

I have a '99 MGF and it definitely does make a difference to the performance and fuel economy, approx. 4 to 5 mpg on average. M11 A14 A1 driving with roof down returned 43/44mpg with super unleaded and with normal unleaded 37/38mpg and not as crisp in acceleration or power delivery; much more torquier.

I know my car has had a few mods done by the previous owner, maybe it has had a remap too.

In general, my costs are about £1.50 more per tankful, enough for an extra litre of unleaded but with 4MPG+ improvement, it by far outweighs the additional cost of the fuel.


By the way, I fill quite regularly in Grantham at a cost of £1.31 per litre for super unleaded, against £1.28 for unleaded.

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by adrianclifford » Wed Aug 08, 2012 5:05 pm

This old post (well it was when it was first started) caught my eye recently for a couple of reasons.

Since my contribution I've changed jobs, I no longer work at the BP station I now drive a diesel Renault Scenic as an Ambulance volunteer driver for the hospital in Chelmsford. This entails a lot of mileage so I stuck to my own words and only used good fuel, usually Shell from one of two local stations. A tankful would take me around 570 miles as she would turn in a daily average of 48-49 mpg (I often carry a full passenger load and a wheelchair or two). After a few months the fuel injection warning came up on the dashboard, investigation showed the wrong fuel had been put in, rubbish but Renault were adamant, the pump and injectors had been damaged. With a repair bill of some £3000 they suggested getting rid of the car which they offered to do (with the idea of me buying another) but it actually made best financial sense, they replaced the pump and filter (£820) and I bought another newer one as the Scenic is ideal for the work with it's high seating. The same week Dawn's diesel Clio (58mpg) had the same warning on the dash, this time it was at home and the RAC were called (before Renault or another local garage) and the engine was not run (she used Pearl for work so there was no rush in deciding what to do). The RAC came to the conclusion that it was bad fuel, the fault was cleared and the car was not used for a while.

With advice from the RAC engineer and as the new Scenic was under warranty I made a decision not to use Shell anymore I decided to throw my hat in the ring, go against my own words and use Tesco fuel, as there are a few on my regular routes ( I use the Tesco credit card for shopping and the points mount up nicely, so I thought, why not ?). The same "rule" was applied to Dawn's car and the results are rather surprising, her car now returns up to 64 mpg and my Scenic regularly reaches 54 - 56 mpg (as it's reset daily it depends on traffic etc). Both cars feel better to drive, more responsive and no concerns at all.

Now to the long reached reason (sorry :oops: ) since then I've used Tesco Momentum 99 (thought I'd support the Racing Team) in Pearl, she's re-mapped and benefits from a good exhaust, Mark Stacey at Z&F Tuning tells me it will do no harm and will show slight benefit when driven enthusiastically (this we like :thumbsu: ). The immediate result was not anything I can really state but it appeared to be a very good response when pushed hard.

On the way to Luxembourg for the recent Tour de Lux with Dawn and I and luggage (and presents and car bits for others) we drove to Dover, off the ferry at Dunkerque and a dash to Clervaux. Saturday saw a fast road run and still a quarter of a tank left, amazing that was close to 390 miles. I would have liked to run it close to empty just to see what fuel I could get in but we needed to fuel up on Saturday as there was no availability on Sunday. The cars were pushed to their limits on Saturday on the twisting, climbing roads so it made the economy rather surprising.

So, if nothing else, the cars like it (especially the Momentum 99), the increased cost is minimal and I get the Tesco points, in fact I got so many last year, £270 worth, I used the double up offer, £540 and put £8 towards it and bought a new Nikon 5100 :D

Recently in the motoring press, increased fuel economy claims were put under scrutiny and none showed up as worth the extra money, I actually beg to differ as I'm sure the car runs better and the economy has increased, albeit some of that must be due to the re-map.
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Re: Will using higher RON or Super Unleaded fuel help my car

Post by Uncletone » Sat Dec 01, 2012 12:06 am

Hi All

Just to throw my ten bobs worth in the ring, does anybody remember when fuel was 10 bob a gallon. Sorry I digress.If you run a car on 99 RON and its set up for 95 to some degree you're not getting the full benefit. Yes there are cleaning detergents in the fuel, but if you want to clean your fuel system and valves, injectors etc you would be better spending your money on a can of BG44K every 12k miles. Ask yourself, why do all the major manufacturers, Audi VW, BMW Toyota, Lexus, stick one in your tank when it goes for a service, because they need to ensure that if there customers engines are running efficiently.
If you doubt the use of fuel additives and oil flushing additives check out the BG site.
A while ago Audi had to find a solution to a problem thay were having with sludge forming in their engines, costing the millions in warranty claims. BG resolved the problem along with the fuel issue . Shell V Power has some additives that will keep the engine clean, but not in the concentration of BG44K.

I worked for Shell for many years and won't use anything else, even their oil as well. Not that there is anything wrong with the other fuels BP, Esso etc its all down to the additives. All fuels are the same...........the basic mix is for want of a better word, but its the additives that go into the tankers that make the difference and its the details of that mix that the chemists keep close to there chests. For followers of Formula 1 look on the Shell website to see whats involved in mixing fuel and the effects it can have on the Ferrari's on a race to race basis..

Just as an aside, BP, Esso, all collect fuel from Ellesmere Port (Shell Depot) but there is only one supplier in the UK that I know of that will guarantee 99 RON fuel ...yep thats right Shell, and guess who provides Tesco with their Tesco Momentum Fuel. So if you're collecting Tesco Club points and if the forecourt is selling Momentum you can bet your bottom dollar the rest of the fuel on that site is Shell as well.

As the threads above say, save your pennies and only use 95 RON if your car is set up for it, and at every service use a can of BG44K in the tank.

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by Green Squirrel » Sat Dec 01, 2012 10:23 am

Unfortunately I remember when it was less than two bob a gallon - for Pool Petrol that is !!

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by benham » Mon Dec 03, 2012 10:24 pm

Fuel system cleaners are a marketed add-on at dealer level. They are used as a KPI and most groups target staff to upsell them, they sell them for terrific profit, I doubt they're even recommended by manufacturers. Same with "air-con cleaners" have a cost of less than £1, easily retailed for £15.

I'm yet (as a lapsed chemist* myself) to find any injector cleaners that are not essentially paraffin.

Having now read the data sheet for BG44K....... I'd chuck a cup of Esso blue in the tank.... Will have a similar effect.

I still think the best method of keeping an engine clean and healthy is regular oil changes and driving very, very hard regularly. I like my engines to " bounce the limiter" at least a few times a week, including my old 325k Cavalier...

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Re: Will using higher RON or Super Unleaded fuel help my car

Post by talkingcars » Mon Dec 03, 2012 10:55 pm

When I worked for the local VW-Audi dealer we didn't offer this to our service customers.
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Re: Will using higher RON or Super Unleaded fuel help my car

Post by Uncletone » Sat Dec 15, 2012 9:55 am

Glad I never took mine there then. I only learnt about this stuff because Audi were putting it in my A6

http://www.bgprod.com/blendr/stickyProblem.html

Esso Blue, I wouldn't use that to warm the greenhouse, I don't know about putting it in my car I'll stick to the BG stuff thanks.
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Re: Will using higher RON or Super Unleaded fuel help my car

Post by Vinyljunkie » Wed Apr 17, 2013 4:12 pm

I've always bunged a tankful of higher RON through all my cars every couple of months if I'm at the pumps and feeling flush. No reason I can give, just seems the thing to do. Cleaners and additives and what not.
How's that for technical. Lol.
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'01 Saab 95 SE est,
'96 4.0l Jeep Grand Cherokee LTD
'81 Honda custom bike
I really need to stop buying things with Engines...maybe there's a support group?
:-)

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adrianclifford
Posts: 8007
Joined: Mon Oct 01, 2007 6:56 pm
MGF Register Region: Essex
Model of Car: MGTF 80LE
Location: Leigh on Sea

Re: Will using higher RON or Super Unleaded fuel help my car

Post by adrianclifford » Wed Apr 17, 2013 4:31 pm

The Scenic and Clio's are still running very well and the same average mpg with the Tesco fuel. Pearl is still happy with Momentum 99 as it's re-mapped to benefit from higher octane. I must say there is a difference as a trial I recently used a tank of Esso 95 octane, no noticeable difference in driving but the exhaust note was not as crisp.
Bilstein shocks, Piper 4-2-1 manifold, Daytona, Vader cold-air induction, custom Z and F Stage 2 re-map, Electric boot release, braided hoses, Blue Magnecor leads, Technozen relays, Stage 1 head, BMW Angel Eyes headlights, "MG" puddle lights.

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hawkstringer
Posts: 95
Joined: Tue Sep 18, 2012 3:22 pm
MGF Register Region: Somerset & Dorset
Model of Car: Mk1 mgf 1.8mpi
Location: Bournemouth

Re: Will using higher RON or Super Unleaded fuel help my car

Post by hawkstringer » Fri May 31, 2013 1:12 pm

Good thread, I have just ordered some redline sl-1. After spending hours and hours of reading forum after forum on the use of fuel additives. Some of you may have heard of a terra clean service. Soon to be prolifically rolled out in uk garages. And available at some garages now. Same kind of thing but does not use carbon based fuels whist cleaning the fuel system. Worth a look anyway. I would prefer to see physical results before and after.

http://www.terraclean.co.uk/

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