I'm sure there's probably been many discussions on this already but I don't see any recent ones.

I know the manual says to use at least 90 octane gas in my 02 S60 AWD. I tried a tank of 89 octane and haven't noticed much of anything irregular.

Am I doing a terrible injustice to my vehicle by using the lesser octane gas?

 

The purists will tell you yes, but my opinion is no. There is nothing wrong with what you are doing. If you don't notice any difference then your fine. I run 87 in mine but with a supplemental additive.

 

I was just going to post a similar message. Last week I accidentally put 89 in our S60 Turbo for the first time; the mileage for that tank of gas skyrocketed from 21 mpg (92 octane) to 26 mpg (89 octane); and I've been doing the exact same driving.

Does the mileage computer just get confused with the different octane or did I stumble on a cheaper golden egg?

 

I tried putting 87 octane in my 01 S60 (three times) and my CEL Light came on with a P0422 Code on it.

Dealer (Service Tech) said to add 93 Octane and clear code and that will solve the CEL problem.

I Did what he said and it solved the problem, but I, being the hard headed person that I am, I wanted to make sure.

I waited about a month and put in 87 octane, the CEL came on with the same code, I added 93 octane and cleared code and I solved the problem.

This time I waited two months and added 87 octane again. Sure enough, CEL came on and same P0422 code.

I convinced myself that, at least with my S60, it is very picky on octane. So I guess I'll stay with 93 Octane

 

thats weird, I have an 01 s80 t6, I've never had probleme with 87 octane in my s80, i put it in a few times..... But 95% of the time i use 93 octane..

 

i belive that we should always treat are cars well, and they will treat us well. so i always use 91 in my t6 but thats here in utah. my buddy that has a 99 s80 t6 put 87 in his, and he car threw all kinds of knock codes. the dealer said that it did a number on his plugs and stuff.

 

I don't doubt that is what you heard, but I do doubt that "it did a number on his plugs and stuff". The spark plug does not know what octane you are running, the spark is not going to change as a result. The timing might, but I can't see how this would affect the spark plug.

For high pressure turbos, yes I can see how you might suffer a performance loss. For my low pressure turbo, and especially if you do not notice any difference, lower octane is not going to hurt anything. My owner's manual states that I can run the lower octane. If your manual doesn't then you shouldn't. However, if the manual says you can, but you are throwing codes with lower octane, you probably need a tuneup.

 

[align=left]how stuff works has the info on octane!
Here is some neat stuff I didn't know
http://auto.howstuffworks.com/question90.htm

Later
Cotton
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