Hi: My 2007 Honda Fit requires 5W-20 oil, but I recently changed the oil and put in 5W-30 by mistake, since that’s what my other car takes, there was a special at the auto store, etc. The engine seems to run fine, but I have noticed a slight decrease in mileage – I usually get ~30 mpg (c…

Effects of using wrong oil weight?

ok4450 October 19, 2007, 11:44pm 6

The oil weight is not responsible for a 5 MPG loss in mileage.
Cooler weather and gas reforumlation may be the cause of that.