Hi,

Just bought a 1990 Iroc Convertible with about 126,000 miles. Would I be shooting myself in the foot if I switch the oil to Mobile 1 10/40 High Mileage Synthetic Oil? It smokes when I crank it now and the previous owner ran 5/30 Mobile in it. I just don't want to do any damage or hurt anything with synthetic oil.

Thanks

 

Blue smoke on startup is a pretty common issue with high mileage chevy heads. It's because of worn valve guides, that let oil seep into the cylinders, after the engine sits for a while. It's not a huge deal, and I don't see why putting synthetic in it would hurt anything. Well, other than the fact that you might occasionally have to add some oil, and synthetic isn't cheap. I also run 10-40, but it's hot here in texas, 5-30 is a little too thin for my liking.