Sorry for the double post, but I'd rather have this topic answered quickyl because there is a sale on motor oil near me and it ends soon...

Basically I want to see if I could use 5w20 oil (synethetic or not) in my 2002 Volvo s40 1.9 Turbo, as opposed to the recommended 5w30 by the manual. I know that 5w20 is a thinner oil and will slightly produce better fuel economy (though most of the times not noticeable), will there be any problems using it? Has anyone else used it? I'll be changing over the synthetic oil soon and I have a good supply of 5w20 (used on other car) and I don't want to go out and have to buy 5w30 oil.
Thanks for the reply guys.

 

I would say as long as you aren't waiting to 7,500 miles to change it you should be fine.
I would change at 3,000 miles.