Which Fuel?

[P_Jazzy]

Whats the best fuel for my AE92 Corolla? I've heard that Super Unleaded gives better economy and performance? Is this true? Its usually about 2-3 pence more expensive compared to normal unleaded?

[System~G]

The engines were designed to run on regular unleaded (95 ron), but super unleaded will only do it good B)

[Twincam.GTi]

Super unleaded such as 'Sheel optimax (About 98 Octain) will be ideal. It is also idea for newer cars if they only do short runs (i.e.School runs and stop starting/local shoping in your high street) for it burns cleaner and over a long period of time can help an older car pass the emission test when it's M.O.T time.

My own experiance is that running my GTi on Super Unleaded all the time is better general running (ideling etc.) slight improvement to acceleration and a clean exhaust tail pipe! Economy I've noticed is no different + as you said it cost a few pence more.

[corollasr]

i find on my 98 corolla that when running on optimax it seems a lot lumpier and loses performance

ed

[Nick-Johnson]

i find on my 98 corolla that when running on optimax it seems a lot lumpier and loses performance

ed

[Twincam.GTi]

i find on my 98 corolla that when running on optimax it seems a lot lumpier and loses performance

ed

I don't see how thats possible. I could fully understand you noticing no difference with a modern car but certainly not hampering performance.

It is I admit more noticeable in an older car. It is ideal in something like a old british banger such as a Mini or MGB where you would have to alter the timing to make it run on 95 octain Unleaded but due to 'Super' Unleaded being 98 octain it was around the same value rating as the old Leaded fuel; thus no adjustment is necessary.

As said earlier I do notice a difference in my 1989 GTi

[Roxtar]

I've read that you should always use the lowest grade fuel your engine will handle without detonation. The higher the grade, the more additives there are to prevent detonation. these additives basically raise the flash-point of the fuel. so if your motor is running hot and you have high compression, you'll get detonation on the compression stroke before the plugs fire if you're running a lower grade fuel. the converse of this is that lower grade fuel burns more completely and more quickly giving you better power and efficiency. so in conclusion,

lower grade burns more completely and faster for better power/efficiency but can cause detonation in high-compression and hot running engines

higher grade fuel is less likely to detonate in performance engines but can rob an engine of some performance if compression ratios are low enough to accept a lower grade

[Twincam.GTi]

lower grade burns more completely and faster for better power/efficiency but can cause detonation in high-compression and hot running engines

higher grade fuel is less likely to detonate in performance engines but can rob an engine of some performance if compression ratios are low enough to accept a lower grade

I see what you mean but...

In Great Britain 'in ye days of olde' the higher the octain the faster the 'motor' went.

There is many a story from the 1930's to 1950's of the R.A.F fellows who used to run there old MG's (e.g. the beautiful PA's, PB's and TA Midgets) on aviation fuel(During the war the only fuel they could shall we say'aquire') which is around 120 octain! the car would go like stink but after a few months there would be many a burnt valve or holed piston!