Thinking about adding some oil additive to my (as far as I know) bone stock, untouched, non-hardened valve seat 1956 Chevy 265. Lucas makes an oil makes 'oil stabilizer' and 'break in oil', only one with ZDDP as far as I can tell, the other seems more like a thickener. If you add this to your motor oil, which do you use? I'm more concerned about engine protection that stopping oil burning, etc.. I know it's a some swear by it, some swear at it topic, and that there are motor oils with protection for older engines, just curious about these products.