My friend just got a 87 GXL. The body is in good shape and under the hood its really clean. The owner say the motor was rebuilt a while back and it has 70k on it now with 150k something on the chassis.

The car smokes a bit when its cold but goes away once its warm. And when he drives it over 5000 rpms its smokes again. It sometimes wont do it.

He wants to know if this is a normal thing or should he be worried?

 

Sounds normal. Especialy for cold weather. Mine used to do it alot to. Just give it about 5-10 minutes warm up time and it wont do it at all... and your friend shouldnt be revving up past 4k if the motor is still cold.

 

Mine does this as well, not the smoking on start up but the over 5k hard shift smoke..... If I miss a shift like get her going in 1st to like 6.5k then don't shift fast into second she'll smoke a nice cloud.. It is a declerating issue. When i first noticed it i thought it was on accel in the next gear but it isn't in most cases. Your friend probably has leaky oil control rings or a crack in one of the seals. Tell him to drive it like a hot stripper untill the seals go POP! Not a big deal and it's great when someones tailgating your ***, whaaaaaa (8k) POOOF smoke screen.......(ODSS) on demand smoke screen! Tell him to enjoy it while it still runs it can't be fixed without a rebuild. I run 20w50 oil and it almost completely solves the problem, but tell him to let the damn thing warm up before driving it.

 

What colour is the smoke? White and smells slightly sweet? Black? white with a hint of blue?

It sounds like oil seals.
Warm up the car.
Rev the engine, transmission in neutral, to 4500 rpm and hold it there for 45 seconds. If smoke starts coming out the back, it means the inner rubber oil control o-rings have disintegrated from any number of causes. The engine itself will be fine, but the smoking might get worse.