Just curious (and probably ignorant). My '90 Vette (with standard engine) will occasionally
expell some gray smoke upon start up. This does not happen everytime I start-up, only
about every 3rd time. Doesn't blow long. I have been burning Premium fuel from quality
stations and synthetic oil. Dipstick doesn't show using oil and oil pressure holds fine.

Any ideas on what causes this and if could be a problem? Thanx in advance.

 

My guess would be slightly worn valve guides, but regardless if it runs fine and does not blow smoke under hard acceleration I would not worry about it.

 

My 90 does the same thing, but does not use a drop of oil, I would not worry about it at all.

 

Could just be condensation burning off. Or you may have 1 or more leaky injectors.

 

Thanks guys......I appreciate your info and timely response...

 

I am beginning to believe that my problem is leaky injectors like you said, sometimes it still is hard to start and I have researched and done several things to it, trying to remedy the situation.

 

Gray smoke = ?
Blue smoke = oil.
Black smoke = rich air/fuel mix / incomplete burn.
White smoke = water vapor/coolant burn.

Startup only (cold motor)smoke (blue) = valve guide seals.

Gray smoke???

Can you get a pic of the exhaust?

 

I'd say valve guide seals are going bad.

My 1990 Corvette was doing the exact same thing. It would periodically blow some smoke on startup but used no oil.

I recently had the heads removed for a multi-angle valve job and new head gaskets. They replaced the seals as a part of the valve job.

That solved the problem with blowing smoke on startup.

Now if I can just find the new oil leak in the area of the oil cooler that's plaguing the car...

Good luck...