Fully Synthetic Oil and Valve Stem Seals

[rcreechssr]

I have an '86 K10 Suburban. Put a new GM "Target" crate engine in about about 60k miles ago. Never had any spark plug issues until started using Mobil1 oil at about 40k miles. Keep in mind this is an old technology, carbureted, non-computerized engine. Noticed the #8 spark plug started getting oil deposits and fouling out. Would foul out even after as few as 300 miles. This was especially noticeable after pulling a trailer. I've decided the valve stem seals are probably letting the "thinner" synthectic oil by. I've gone back to conventional 10w30 Valvoline that I've used for years. So far so good, but only about 200 miles so far.
Does anyone any thoughts on this? Will the problem rectify itself or will I still have to change valve seals?
All thoughts and comments will be greatly apprecitated.
rcreechssr

[rcreechssr]

Helllloooo. Anybody home?

[Jake_reps337]

Have you done a compression check? Oil being the cause of this problem is unlikely.

I'm guessing the engine is burning oil? (white smoke comes out the exhaust) the carburetor may have gotten some trash in it, causing it to run rich.. try some carburetor cleaner and see if that helps.

[rcreechssr]

Originally Posted by Jake_reps337

Have you done a compression check? Oil being the cause of this problem is unlikely.

I'm guessing the engine is burning oil? (white smoke comes out the exhaust) the carburetor may have gotten some trash in it, causing it to run rich.. try some carburetor cleaner and see if that helps.

Thanks for your reply. Compression is good, I'll try the carburetor cleaner (good idea). White smoke puff only after sitting for a week or more. Since I went back to conventional oil, no smoke. Still less than 300 miles on plug change, still running good, no misses. If you're right about oil not being the problem, then I guess I'm looking at new valve seals.
Randy

[88redlegend]

Originally Posted by Jake_reps337

Have you done a compression check? Oil being the cause of this problem is unlikely.

I'm guessing the engine is burning oil? (white smoke comes out the exhaust) the carburetor may have gotten some trash in it, causing it to run rich.. try some carburetor cleaner and see if that helps.

Just fyi white smoke is coolant/water blue is oil and black is to much fuel.

[jwko]

It's your valve seals. Pretty easy to change out. Disconnect your quick connect hose from your compression tester, screw in a plug hole and attach an air hose on the other end. The air will force the piston down & hold the valves up. Easy on the air pressure though. Use A small clamp type valve spring compressor, compress the spring then remove the two keepers & remove the spring. Off with the old valve seal on with the new. Back on with the spring, then the keepers (little dab of grease on keepers will hold them in place), make sure they seat correctly. Remove the spring compressor and lightly tap the top of the valve stem to insure the keepers are in place. Don't remove the plugs from all the cylinders as you do this, one at a time then replace as the air will spin the motor over.