M42 guys using 87 octane: read this.

[christophbmw]

I hope im not the only one who has done this but heres my discovery: When i first bought the car 18 months ago i put 89 octane fuel in it because thats what i put in my older M10 before i totaled it. it ran fine, or so i thought. any way about a month ago i switched to 87 octane. i did notice it ran like shit at about 3 grand up to about 4500.....but no pinging, so i kept useing 87. yesterday i ran the tank all the way empty and filled it with 91 octane (just to see what would happen). man what a difference! it runs great now, i know im a dumbass for using 87, and im here to tell anyone who uses 87 to switch to 91 (if anyone still uses 87), i also noticed in the manual that we should use 91 (should of read it when i bought the car.....oh well).

never would have thought 4 octane spread would have made such a difference. now i just gotta use race fuel (hope i dont burn the cat.)!

[Jarvis]

I think you're the only one dumb enough to use 87 octane in an engine with 10:1 compression and no knock sensors. Oh wait, this is R3V so you're probably not alone.

[DoriftuEvo]

Atleast he's not claiming the higher octane made his car 10 times faster as I've seen many times before.

[wastedincome]

I think you're the only one dumb enough to use 87 octane in an engine with 10:1 compression and no knock sensors. Oh wait, this is R3V so you're probably not alone.

The owners manual even says that the m42 REQUIRES high octance fuel. NOTHING under 91 should be used

[Axxe]

What a t00l.

[KenC]

Read the octane rating carefully. Europe uses different octane rating numbers. RON and PON are different. The US uses PON which is "4" lower than RON, which Europe uses. Thus 91 RON (which it says in most manuals including mine) = 87 PON.

[christophbmw]

The US uses PON which is "4" lower than RON, which Europe uses. Thus 91 RON (which it says in most manuals including mine) = 87 PON.

my manual also says 95 RON.....thanks for explaining, geuss its the same as 91 PON.