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oil cause unholy gas mileage?

Posted: Tue Mar 23, 2004 4:24 pm
by azn2nr
i changed my oil to 10w 30 about 2000 miles ago before the coldest winter on the books for ten years came around but for the last few weeks i loaned my car to a friend who had his in the shop. a week before he gave it back he told me it was sucking gas like none other and now that i have it back the mileage has gone to 12mpgs from about 21mpgs. is it posible that the warmer weather and thicker oil is causing the problem???

Posted: Tue Mar 23, 2004 6:12 pm
by DLC
I'm going back to 15w40 on my next oil change. Oil viscosity has very, very little to do with gas mileage. Drive it another tank and see what it gets.