Hey, 93 Suburban 350 5.7, 160k original, light white smoke on startup, heavy on accleration, no overheating, no oil in water, no water in oil, compression within range, no missing, does not seem to change or go away after normal operting temp. smoke does not appear to have blue tint and does not smell like coolant however it appears to have moisture within. Sound like Valve guides or head gasket(s)? Does synthectic oil burn like crude oil (smoke or no smoke) for diagnostic purposes? High percentage of mass oil leaks if synthetic swithed temporarily? Currently regular 20w50 is sitting in the pan. Thought it may have been intake gaskets, leaking into a port, swithed um out no luck same thing still goin on.

bad valve guide seals would cause smoking...how has your oil level been?

Not too bad, but havn't drove it far enough to really see, with all the smoke you tend to have alot of attention from the neighors and other motorist, but I will try to drive it more during the evening when the smoke isn't as visable. ( It is a second vehicle not used yet for transportation.) What about the synthetic test, think its works, or just a big mistake, don't feel like doing a rear main right now.

synthetic will tend to find leaks, because it is so fine....the viscosity is so low, it finds small leaks...but im not sure how it would affect the smoking...

I suggest buying a quart of Oil additive (Lucas High milage or Slick 50) you can either drain a quart before adding this or completely change the oil adding the additive first before the rest of the oil. For your application I reccomend using Castrol GTX for High milage vehicles. (my father uses this in his 99 2500 with 240K miles and it corrected light smoking from the tailpipe)

You could have bad valve stem seals and or worn valve guides, but it sounds like your oil rings are bad.You can have good compression and still have bad oil rings. Power punch/motor honey will make the oil thicker and therefore harder to get by the rings or valve guides.It has worked for me, it's only a bandage, but it is cheaper than a new engine .