My son and I recently rebuild the engine is his '86 Buick Grand National. For those of you who don't know what it is, the powerplant in this car is a 3.8 liter intercooled/turbocharged flat tappet cammed OHV engine. The original factory oil recommendations were 10w30 or 5w30 for colder climates. We live in Florida, so 10w30 is a natural choice, but the oils are so much better than they used to be, I was thinking of using Pennzoil conventional 5w30 year round for the better flow at startup, along with 5-6oz of Lucas TB Zinc plus to protect the flat tappet cam. TB Zinc Plus is a pint that delivers 38,000 PPM Zinc, so I figured 1oz per quart should cover me. What do you guys think?