I have an oil leak at valve covers after changing to Mobile 1 oil. I had the valve covers changed still leads a little but not as bad. Car did not leak before changing to mobile 1. Is this common and should I change back to regular oil?
If the leak is from the valve cover, I don't think it is due to the oil you use. When replacing the valve cover gasket, if non OEM gaskets are used, they might leak. The other thing is proper torquing. Improper torquing can result in the valve cover cracking and leaking. Recheck the work done.