Ron + Mon / 2 = 91

[Hendog]

I've read much on this BBS in regards to octane. I especially liked the discussion here started by Nixter. Since I downgraded to 87 octane...

But my car is not an SC, but rather a 3.2 Carrera with a Motronic. The fuel door indicates RON + MON / 2 = 91. It has a Autothority chip (PO put that in; I would have gone SW of course); SSI heat exchangers and a dual in / single out muffler (not sure what brand).

With the price of fuel at $1.05/litre, I sure would like to be able to justify running 87 octane fuel. I've just tried my first tank of 87 and am only half way through it; no noticeable difference (yet?). It's still early to tell, but I think the mielage is better(??). Should I abort the use of 87 and stick with 91?

[RickM]

The Autothority Chip came with a sticker that insists the customer use 92 (or was it 93) octane fuel. I would not fool with lower octane product if you indeed have a tweaked chip.


EDIT: It's 92 Minimum

[450knotOffice]

Your car was designed for the higher octane gas and you have a performance chip in it. Do yourself a favor and stick with the more expensive gas. It's a lot cheaper than a potential top end rebuild caused by detonation.

[TerryH]

You might get away with lower octane on a cooler day when the air is more dense. As the days grow warmer you may ruin your motor trying to climb a hill if you are under-octaned.

[Hendog]

Thanks guys. I have no problem paying for the fuel if it is warranted, I just didn't like the idea of wasting money: High octane it shall be.