I just bought my '86 Cutlass as a new project. I notice a puff of blue smoke when I start it up, but it doesn't smoke any after that. I'm thinking the valves seals are leaking oil into the cylinders but was just curious if anyone else had an opinion.

 

You are probably starting in the correct place. Check valve stem oil seals and guide wear. Other ways for oil to get in are worn, broken, or sticking piston rings, and, on some automatic transmission cars, a connection between the transmission and the intake manifold.

 

Yep, valve stem seals are my first guess.
If they are bad enough, then it will puff a cloud again when accelerating after prolonged idling.

 

Other than the aggravation of seeing the blue smoke, if car isn't losing a lot of oil you should be OK for a while. If the car runs smooth and you're getting at least 1000 miles on a quart of oil I wouldn't worry about it a lot.

 

Yeah, It doesn't seem to be using alot of oil and the motor runs like a top other than that. It's just sucks when your trying to look cool then those little puffs of blue come out.

 

Well, I have seen many 2000's cars belching more than a puff of smoke, mitsubishies the most common.

Changing the valve seals mean pulling valve covers, which may already be leaking. On the 307, that job is a PITA to say the least.

What oil are you using? Perhaps use the thickest you can for your particular climate. This might help reduce the smoke a tad...
Then prepare for a stem seal change. Use felpro permadry+ valve cover gaskets for the best seal.

 

Anybody says anything tell 'em it's burning off the residue of the last car you smoked at the stoplight.

 

I would've never tried it without my son telling me how we it worked for him, and it worked for me!!
Slick 50 and high-mileage oil cuts oil consumption by a lot!!!
Really helped my '89 Suburban w/157 k!!

 

My 88 Caprice (305) which was well taken care of at about 90 K started to blow a puff of blue upon start up. When it was finally down a quart it was time to change the oil anyway, about 3,000 to 4,000 miles. I piled another 50 K on it without a problem, unless you have to add oil I wouldn't worry about it. Enjoy the puff.

 

i'd start by replacing the PCV valve...least expensive and quite common