what oil to use
I spoke with a friend of mine that is involved with NASCAR. I had him ask around to get the scoop on this zinc / oil subject.
What I got back were a whole bunch of explainations from the likes of Petty Enterprises, Jack Roush, Hendrick Motor Sports and MOPAR engine guru Joey Arrington.
In a nut shell, what they all said was this... Zinc is in the oil formula as a wear prohibitor, but the word prohibitor should be used in the sense that it slows down wear progression over time. The key here is the term "over time".
They all agree that if you change your oil religiously (every 2-3K miles in a street car), that the zinc issue is NOT AN ISSUE.
They also went on to state that zinc is helpful in engines that are run in the 7000+ RPM range because of the heat generated, and the acceleration of the oil breaking down because of it.
For high RPM applications (all out race cars and motorcycles) zinc content is a viable concern... for the rest of us, it should not be a huge concern!
Also... if you are wary of the zinc issue, you can convert over to a synthetic oil. Synthetic oils use different chemical compounds that resist wear. A true synthetic oil does not contain zinc at all.
Just my $0.02 worth of input... but it makes sense to me.