Originally posted by motu
OK so I was changing my oil myself for the first time today with the help of my cousin. Halfway through pouring the new oil in I realize that I picked up the wrong bottle from the shelf. My manual says I should use 10W30, but the stuff I just poured in was 10W40. Is this that big a deal? Can I hold off until my next oil change to correct it or do I need to change it NOW. I will be driving from Florida to Michigan in two weeks, but it is still too early in the year for drastic weather changes. Please let me know ASAP!! Thanks!!
It won't hurt at all. as the prevous dude said your MPG will suffer a little bit. To be honest i think it will actually be better for your car.
If your driving from Florida to Michigan in August that is pretty much the ultimate exteme for your car. Long high speed driving in hot weather will breakdown the viscosity of your oil more then anything. The 40 weight oil will protect better under these conditions.