The 350 in my 89 k5 runs great but lately when I run slowly (almost at idle) around my hunting club it will start to smoke. It'seems blue and smells of oil but the engine doesn't appear to be using any. Once you run at speed it stops smoking. I had a similar issue a couple years back but changed the intake manifold gasket and the smoking and sucking air noise stopped. Any idea what could be going on. Doesn't smoke any time but running slow.

 

valve guides are notorious for going out on older chevys. my 90 always does that puff of smoke when i start it up and my 86 smokes for about 5 minutes then clears up. maybe add some lucus oil treatment or some other kind of snake oil to see if you can get those valve guides to reseal.

only takes a few drips to make it smoke. my oil barely goes down in my 90 i drive everyday i might have to put a quart into it between oil changes but i also have a rear main leak