Quote:
Originally Posted by theastronaut
Zinc/ZDDP is a "last ditch effort" type of lubricant. It really only comes into play after the oil film's strength has been exceeded. Too much ZDDP can be abrasive- that's why you find high levels of it in break-in oil, the engine breaks-in quickly that way. The best oil has a high film strength, and enough ZDDP as "back up" protection but not too much to be abrasive.
Oil thickness is determined by your bearing clearances. New/tight engines don't need thick oil. The bearings are cooled by oil FLOW through the bearings. Thick oil doesn't flow, especially through tight bearing clearances. Older/worn engines can use thicker oil since there is room for the oil to still flow. As for oil pressure, you only need 10 psi per 1000 rpm, so use thinner/thicker weight oil to adjust your oil pressure. Use as thin of oil as you can do you get the best flow and adequate pressure.
Good info on film strength here.
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That is new info to me thank you so much! I've been meaning to ask what's te right PSI, my truck isles at 39 Psi at idle, I have my truck idling at 700 RPM's, and right now the truck has 5w/30.... Is that good?