My 87' Chevy Blazer 4X4 started blowing white smoke from exhaust a few months back only on start up after sitting for some time. It has a 350 C.I. engine with 177,000 miles. Now I have white smoke coming from exhaust more frequently and sometimes I notice it even when truck is running, not just on startup. I know the engine must have seals somewhere that are allowing oil to burn off where it's not supposed to be. Can I get a more detailed explanation about the cause and what I can do to clear it up. A friend of mine suggested running a heavier oil,(20-50 Wt), that would be less prone to seep through old seals. Am I headed for a major engine repair? All comments appreciated.