I just purchased my first Volvo for my 16 year old son. It is a 1997 S90 in excellent shape, everything works great on the car. The only con is that the car has 230K miles on it. I called the original owner and he gave me the scoop on the vehicle. The trans was changed about a year ago, the timing belt was recently done and he has always ran synthetic Mobil One 20W50 in it. I've searched the web about oil and the highest recommended rating I've seen is 15W40 for extreme conditions and weather. I do live in south Texas so you could probably call it extreme weather conditions for some.

Anyway, on to my question. Should I stay with the 20W50 Mobile one or switch to a more appropriate Oil weight for the vehicle? I'd like to drop it lower say 15W40 or even 10W40 but it's hard to argue with 230K mile and still runs perfect?

Thanks,

Tim ONeil
South Texas

I would run 10W30 or the 15W40 if the weather conditions warrant the heavier weight oil. I run Mobil 1 10W30 in my 97 960. If the weather is under 90 degrees you should be fine with the 10W30. In the summer I would run the 15W40. I don't know what is with Volvo owners who think 50 weight oil is best for their car.
You said the car still runs great after 230K you can hang your hat on the Mobil 1 oil for that engines longevity. One point with these engines is DO NOT extend Volvo's recommended intervals. They are not as forgiving as the old I4 B230's were to neglect.
A great place to read up on the quirks these cars have is over on the Brickboard's FAQ for 960's. http://brickboard.com/FAQ/700-900/960_90Info.htm

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