Hi everyone, I've been trying to talk my father-in-law into using Schaefer's oil in his '94 Corvette (5.7L engine (I think), 35th anniversary car). However, he doesn't want to because he "heard" that running a synthetic oil after using conventional oils will "hurt" his engine. The engine has ~115K miles on it and is not (noticably) burning or otherwise using oil between its 3K mile oil changes. I thought this was just rumor and heresay, but he it pretty adamant about it unless I can come up with some information that shows otherwise. I'm also waiting for him to get an oil change so he will use the oil analysis kit I bought him so we can see exactly what is going on inside the engine. Any help? Scott PS. He also has a 4 cylinder Camry that Toyota replaced the engine on due to the oil sludge/gel problem they've got (~3K-4K oil changes, religiously) and I've been trying to suggest that a synthetic (namely Schaefer's) would also help with that car.