88 silverado with valve seal problems

[88chevy]

ok i just bought my dads old 88 chevy silverdao reg cab longbed from the guy he sold it to years back. when my dad sold the truck it ran like a top but smoked the first couple minutes after you start it. my when it started doing it my dad put engine restore in it and it stopped for 2 months. when it started again we quit driving it and sold it. it was sold 3 years ago parked and left sitting. it still runs fine but is smoking horribly. i have ran a compression check and all 8 cylinders still have really good compression. so can it be the valve seals are bad? if so would putting a 15 or 20 wait oil in it help it enough to where i can drive it for 3 months until i get the money for a used 350? any help or ideas are greatly appreciated.

[Jimmiee]

If the valve guide seals are leaking thicker oil will not help. You can change the seals without taking the heads off.