95 or 98 ron petrol?

[s-line stu]

The manual for my 1.8T 190 recommends 98 ron minimum i.e. Shell V-Power or similar (I am also running Custom Codes stage 1 remap).

Generally I have been using V-Power but the last few tanks have been regular 95 ron due to V-power not being available at my nearest Shell station and I can't really say I've noticed any difference.

Fuel economy seems the same and there's doesn't seem to be any noticable difference in performance.

I will still use V Power most of the time but just wondered what everyone else uses? Are you all sticking to 98 or are you using 95?

thanks,

Stu

 

[golf]

I use high octane stuff just because it's probably better for the engine.

Can't say I really notice that much difference if I use regular stuff every so often, I think the effects are only felt after a few tanks worth of petrol.

 

[tractorman]

Dont think Ive ever used the 98 stuff in my S4, and it runs fine. The nearest garage that has it is 50 mile away, normal petrol here where I am is 121.9p, which is dear enough.

 

[J7USS]

I always use V-Power or BP Ultimate.
Ran mine on 95 before and its ok having the odd tank of 95 but after a few tanks, mine starts to sound a little rough. Soon as I switch back to V-Power its fine again and defo tell a difference in Performance.

 

[JamesS4cab]

I tried running my S4 on 95 for three tanks to see what it did, and it ran rough as old boots. Switched back to 98/99 and after two tanks, it was smooth as you like.

You do need to run a few tanks through it to allow the ECU to adjust.

 

[J7USS]

Dont think Ive ever used the 98 stuff in my S4, and it runs fine. The nearest garage that has it is 50 mile away, normal petrol here where I am is 121.9p, which is dear enough.

Seriously you wanna try a couple of tanks of the V-Power, you soon see the difference and what we're talking about.
V-power here is 121.9p at the min, even if its 130.odd by you, you should still give it a go!!

 

[Bong Water]

Just put 95 RON in my 1.8T A4 for the first time since I have owned it which is 7 months due to availability of SUL in my area, cant seem to find any difference TBH, not been driving it hard though

 

[Macduff]

All the cars that require 98 WILL run OK on 95 but with reduced power and possibly reduced MPG. Simple as that.

 

[Nickynibbles]

All the cars that require 98 WILL run OK on 95 but with reduced power and possibly reduced MPG. Simple as that.

I once did some testing on my A4 3.0 qs and did notice a slightly better mpg on 99 RON compared to 95 RON which made up for the difference in price. The difference was most noticeable when I started using 99 RON in my motorbike, you could really notice the power difference just by riding it so I know it does what it says on the tin!!

 

[J7USS]

Yeah as macduff said they can all run on 95, we know that but it'll run alot better with 98+. 95 is **** . Ok for emergency fill up. Thats my opinion anyway

 

[JamesS4cab]

Agree with J7USS - they will run fine, but it takes a while for the ECU to adapt to the change in fuel.

Give 98/99 a few tanks and then decide.

 

[ScottyP45]

Agreed too, I always use 99 octane tesco super, but occasionally have to use 95 crap. Its only 4p more here per litre so whats the point eh unless you need some and cant get the usual, but then I only put enough in to get home and use tesco the next day to fill up, £80 a tank.

Incedentally, the difference between 95 and 98 or 99 is to do with knock or detonation resistance. Higher octane fuels make more power available but not because they burn more, but they have extra fuel molecules left over.

Ideal Stochiometric Ratio is 14:1 (air/fuel mix ratio in the cylinders) and when running high compression motors or turbo boosted ones then more compression or boost can be applied without deadly detonation occurring since the extra fuel particles cool the charge. The engine cant burn much more or less than 14:1 since thats fixed by chemistry and only changes slightly through out the rev range.

When you run a turbo or other hot motor on 95 octane the knock sensor will ****** the ignition and cam timing (if variable) to prevent it and this reduces available power.

Stick 99 or 98 in and the ecu can hit full MEP (mean effective pressure) in the cylinders and the knock sensor will report no or very little detonation, so the engine is more powerful and lively, but it always had that power and low octane fuels only force retardation and loss.

Mild "pootling about" drivers probably won't notice much difference unless towing a lot or carrying passengers...it only affects the engine when you open it up a bit

 

[J7USS]

....well scots, you done it again....Im ****** Lost.hahaha..
Ive just read that out to the Mrs and she just glared at me and said "and"!!!!


Dont think I dare call you thick..

 

[ScottyP45]

LOL my missus is the same! She just hears "blah blah blah" when I try to explain something to her about cars....I have given up

Sorry if it got wordy but in a nutshell 98 / 99 prevent "pinking" and so the ecu can apply more power / boost, 95 causes the ignition timing to ****** quite a bit under load so less grunt is available and the engine will feel weaker.

 

[quattrojames]

:sign_ot: Slightly, but has anyone tried v-power diesel or similar? Whats the difference between normal diesel and v-power does anyone know? Is it just improved detergents in the fuel, or more to it ....?

 

[ScottyP45]

Mainly reduced sulphur in the exhaust mate. I noticed an improvement in my diesels using sainsbury low sulphur City Diesel, much more poke in the Alfa TDi but cant say shell seemed any better than normal stuff, probably better over the long run. Sulphur causes deposits and robs a bit of power from a diesel...

 

[J7USS]

LOL my missus is the same! She just hears "blah blah blah" when I try to explain something to her about cars....I have given up

Sorry if it got wordy but in a nutshell 98 / 99 prevent "pinking" and so the ecu can apply more power / boost, 95 causes the ignition timing to ****** quite a bit under load so less grunt is available and the engine will feel weaker.

Im with you now..

 

[Macduff]

I once did some testing on my A4 3.0 qs and did notice a slightly better mpg on 99 RON compared to 95 RON which made up for the difference in price. The difference was most noticeable when I started using 99 RON in my motorbike, you could really notice the power difference just by riding it so I know it does what it says on the tin!!

I've tried it in my bike and noticed no difference at all. That'll be accounted for the fact that the ECU doesn't have the parameters to take advantage of 99.

TBH, I think a lot of people want it to be better so they believe it is. If your car says it needs SUL then OK but if it only needs 95 then it's unlikely the ECU will adapt to use SUL and it'll just be a waste of money

I got suckered with the whole BP Ultimate diesel thing a year or so back. I ran it exclusively for several tankfuls and noticed no difference in MPG although it was perhaps slightly smoother and quieter - not worth the extra cost IMHO

 

[Nickynibbles]

I've tried it in my bike and noticed no difference at all. That'll be accounted for the fact that the ECU doesn't have the parameters to take advantage of 99.

TBH, I think a lot of people want it to be better so they believe it is. If your car says it needs SUL then OK but if it only needs 95 then it's unlikely the ECU will adapt to use SUL and it'll just be a waste of money

The same goes for bikes & cars, you need to have an adapting ECU to notice any differences at all. If your stick it in a car/bike with a non-adapting ECU your just wasting your time as it wont change the ignition & injection to compensate & thus increase the performance. I was lucky with my bike as when they changed the model they binned the carbs to stick a pukka injection system on the bike instead

Most modern german petrol cars seem to be fitted with the right technology to take advantage of this so stick it in your Audi with the assurance it does actually do something!!

 

[Macduff]

The same goes for bikes & cars, you need to have an adapting ECU to notice any differences at all. If your stick it in a car/bike with a non-adapting ECU your just wasting your time as it wont change the ignition & injection to compensate & thus increase the performance. I was lucky with my bike as when they changed the model they binned the carbs to stick a pukka injection system on the bike instead

Most modern german petrol cars seem to be fitted with the right technology to take advantage of this so stick it in your Audi with the assurance it does actually do something!!

I guess it very much depends on the bike/car. My VFR states 95 and I know it won't adapt to use 98 so it's a waste to use it. I was under the impression that most bikes were the same as they don't need 98.

I was under the impression that if a car required 95 then it wouldn't adapt to 98. However if it requires 98 then it must be able to adapt to 95 as that's the standard fuel on sale on Europe. I don't believe it takes several tankfulls as some have said as that could result in engine damage. The ECU monitors the knock sensors constantly and adjusts the ignition immediately to suit.

 

[Nickynibbles]

I guess it very much depends on the bike/car. My VFR states 95 and I know it won't adapt to use 98 so it's a waste to use it. I was under the impression that most bikes were the same as they don't need 98.

I was under the impression that if a car required 95 then it wouldn't adapt to 98. However if it requires 98 then it must be able to adapt to 95 as that's the standard fuel on sale on Europe. I don't believe it takes several tankfulls as some have said as that could result in engine damage. The ECU monitors the knock sensors constantly and adjusts the ignition immediately to suit.

Any car/bike whose ECU can ****** the ignition would show a benefit from running 98+ RON fuel even though the manufacturer has tuned the car/bike to run on 95 RON and recommends this fuel type. I remember from a friend who had an Suzuki SV650 a few years ago that it was popular to add a tiny piece of metal to the distributor I think it was that would basically mechanically ****** the ignition and increase the bhp a little. As long as it was run on super unleaded pinking was avoided, a cheap mod basically that is replicated with modern ECU's that can ****** the ignition for you.

I think the "several tanks of fuel" theory is based upon the system having lower grade fuel in it still so you get dilution. Indeed the ECU monitors and adjusts things immediately but they have the ability to remember the drivers style so if you drive everywhere not using full throttle, after a while the ECU wouldnt actually open the throttle butterflies all the way if you did happen to floor it. Its something I learnt from my Smart roadster but if you disconnect the battery of the car to reset the ECU it forgets your driving style & will open the butterflies completely if you floor it. Its recommended to be done on the Smarts every few months to keep things working 100% but applies to any car/bike really. Certainly worth doing if your going to try out super unleaded as a result of reading this thread!

 

[Nilz]

For what its worth, I have an 8L S3, when i first got it, i ran normal unleaded on it as thats what the previous user used and consistently for the 1st couple of weeks i was getting roughly 320 miles out of a full tank, but since i started using SUL (Shell V-Power) I am now regularly getting 380-400 miles per tank, so im getting on average an extra 60-80 miles now, which compensates for the extra cost.

Also just for information, I am running on average from the DIS 30.7mpg and the majority of my driving is done on the motorway.

Cheers
Nilz