Originally Posted by BestXXXPorn

That's not correct, you can have a head gasket leak that leaks in coolant and/or oil into your cylinders which would put all the smoke out the ass end of your car...

Does the smoke smell at all? It could be that a coolant channel is leaking into the head... or oil... a small leak will barely be noticeable on a compression test... a small leak can be within the boundaries of "ok"... White smoke is usually a coolant problem so I can almost guarantee you have a head gasket leak... it's probably just a small one. A tiny bit of coolant makes an enormous amount of smoke :P

Anyway, may I suggest a new mechanic? He should have tracked down the issue by now.