95 RON is OK in a standard 8v digi as the knock sensor (if working) can retard the timing to make it safe but you will not achieve the rated power, if you want to be sure of getting the full 112bhp (ish) then you must use 98 RON.
You should not use 95 in a k-jet if you drive it hard at the standard ignition timing. If you want to use 95 all the time you should retard the timing by 3 to 5 degrees which will reduce the power a little but will help to prevent 'pre-ignition'.........to a point.........
If you have an old worn engine with poor compression you'll probably get away with 95 RON without 'pre-ignition', however, if you have an old engine in good condition with plenty of carbon deposit, this can raise the compression ratio along with producing 'hotspots' in the cylinder which would raise the risk of 'p-i'. In this situation using a RON higher than 98 could be safer for the engine.
Pre-ignition normally starts at a point in the rev range where the maximum torque occurs, around 3000-3500rpm in an 8v and 4200-4700 in a 16v. it does not normally occur at very low or very high rpm.
If your engine is running too hot it will also increase the risk of 'p-i'. If you're lucky you will hear 'p-i' as a 'jingling' sound and you can ease off the throttle but most people just can't tell, that's why knock sensors were invented to listen for us.
Surely this must be locked off soon.................zzzzzzzzzzzzzz
