fluffyninja

I'll bow to better knowledge of the specific ECU set up but the principle of the engine control system is it will advance the timing until the knock level in the engine reches a certain threshold level. Once it crosses that level it retards the timing until it drops back below it so the engine constantly tunes itself.

There's no specific sensor that recognises the RON level of the fuel being used. It's the effect of it in the engine that determines how the engine interpretes the results

Kelk

I can certainly tell the difference between non "supre-fules" and normal stuff I'd stick in the beater. The car becomes sluggish and generally appears to be feeling

I don't put Ultimate in anymore either as the local BP garage seems to have dirty tanks / lines that made the S feel again. So I stick with Opti and my baby loves it......

Cue everyone's favourite fuel discsussion

ge2

Mine felt like it didn't want to rev on normal UL, probably wasn't any quicker on Optimax but just felt a lot smoother.

Have only ever run the S on Optimax other than a few emergencies where I've only put enough in to get to the next Shell garage. I'm tempted to try a full tank of normal stuff to see the difference but it would make me feel a bit guilty

mikdys

The sticker inside the fuel flap on my S states to use 98 Octane fuel although this is not omnipresent at UK forecourts (unlike Spain where I found it on every forecourt I visted, irrespective of fuel brand). Honda wouldn't have put the sticker there for no reason, I don't need to know the trechnicalities, I am just looking after my car by following the manufacturer's recommendations in using 98 Octane.

The main reason I use Optimax is that I know if I stop at a Shell forcourt its going to have 98 Octane fuel (apologies to BP, Esso, etc if the same applies - I'm not sure that it does though - but I find the Shell marketing message is stronger!). I also like to believe that Optimax has detergents that keep the inlet tract and injectors clean but, even if this theory were to be debunked, I would continue using the fuel for the octane rating.

On the subject of Shell fuels does anyone remember the last time they tried marketing a premium brand fuel in the mid 1980's? They may have got it wrong then as, allegedly, it used to burn up exhaust valve seats in volume marque cars as soon as look at them. This memory made me a bit nervous of using Optimax at first (I seem to remember the rumour went along the lines of "the tanker drivers used to pour in an additive at the oil depots and didn't measure the quantities too well") but I have run a lot of miles on Optimax now with no problems and I haven't heard of anybody else complaining either.

steve_the_greek

So, they do a test on a engine designed for 95RON, and feed it SUL, and it doesn't improve the performance. Well what a surprise
A more useful test would have been to put a car that is supposed to be run on 98, like many of the Japanese performance cars, or the new breed of VAG FSI engines.
Personally, I normally use Esso SUL as it's the cheapest major branded SUL on my commute. Never noticed the difference compared to Optimax or Ultimate.

markS2kcU

Just going a bit off topic, has anyone been to Europe and tried that shell V Power, isn't it 100 RON? any notable difference using that?

mec

I think V-power is the same, and i thought optimax starts out at about 100ron but the detergents in it bring the ron value down over time. So if the filling station doesn't sell a lot of the stuff and it sits in their tanks it could be less than 98ron. This could all be a vicious rumour though.

Personally i run on Optimax only, at 9,000rpm you want to know that there is no knocking going on, even if it has a bloody clever japanese ECU in it. Also Shell not being american helps to (sorry read too many of those Michael Moore books).

Neil.H

I'm no expert on this but surely you won't see any significant results on any kind of car after one gallon of fuel! It takes a lot more than that before you see any changes.

I use Optimax because it's higher octane and on a high compression engine like ours it does matter, I'll leave the muppet who wrote this article to think what they like.

PSC

Well I run my car on Shell V-Power 93RON ULP while at altitude and 95RON at the coast (sometimes less as there is a mixture of 93/95) without any ill effects.

We can get 97RON ULP from (engen/petronas), which I have tried, however it doesn't appear to have as crisp a response as the V-Power.

Honda ZA has no qualms about running on the lower octane at all (the manual also states that the car can be run on 95RON and only references 98RON for some other countries).


-- Paul

supers2k

I ran my old S on Optimax religously but in my new S, I have not been as strict.

I only ever use SUL however but have tried Ultimate, Esso and Sainsburys SUL due to a house move and Opti not being as readily available.

From what I have seen, my car seems to run better on SAINSBURYS SUL then the others which is 97 ron. I stuck some Opti in at the WE and the car seemed more 'relucatant' then the previous tank which had been Sainsburys own.

I therefore now stick to Sainsburys SUL which is 80.9 ppl where I live whereas opti and Ulti are around 88/89 ppl. Also if you shop in Sainsburys like me and spend over