Quote:
It would also be interesting to know how much of a MPG hit they take, using significantly heavier oils...
In my Camira (1.8 ltire J-Car Wagon), I changed from 15W-40 to 25W-70 in the middle of winter (gets down to minus 7C occasionally, have some days that it doesn't get above 1 or 2C).
Mileage took a solid 10% hit.
Went to straight 30 that summer, and the mileage was back to where it was 15W-40.