Re: recommended oil weight
 

Everyone is worked up on the zink but does the engine have flat or roller lifters? What about bearing clearance. Thicker oil is great for the looser builds of days past. Go too thick on a modern tight build and you will be sorry. Most above suggestions are not taking into account your engine may be very different than theirs. All the zinc in the world will not help a tight bearing in a cold engine with high viscosity oil. If you can't find the engine specs, I would run high zinc with moderate viscosity. Run a Blackstone report when you change and continue till you find what works best.