Hi everybody, First time poster here and will thank all of you in advance for all your help. I have a 1988 stock Corvette convertible with 70K miles. I've been reading that the amount of zinc in engine oil has been reduced several times in the last few years. Some of these articles say that older engines, high performance engines and hot rods can be damaged by using oils with these lower levels of zinc.
I'm currently using Mobil Fully Synthetic 5W-30
Can anyone tell me if this is a good choice or are there better choices available for my C4?
What do you use?

 

I don't think there is a "better" oil for your C4. This is the first I've heard of this zinc thing and from what I know about oils I'm definitely not losing any sleep over it. Any metal in the oil would be minute and inconsequential,the lubricating is done by the oil. For heavy duty use in your vet such as racing or towing,I personally would probably go to a little heavier oil,maybe as much as a 15w-40,no heavier unless the engine is totally worn out then I'd probably rebuild it rather than go to the heavier oil. Again personal preference has me using minimum 10w-whatever in engines with timing chains and reserving the 5w-stuff for belt type engines. Go with the owner's manual and you'll be just fine.
Ron

 

The problem with going with what the manual recommends is that it was created prior to 1988. The regulation that changed how much zinc an engine oil contains was change in the late 90's. Not sure of the exact year. I think by reducing the zinc levels the oil was suppose to burn cleaner and it was suppose to make the catalytic converter last longer, but it also caused premature wear of the camshaft on older flat tappet pushrod engines.