So the head gasket on my truck blew and there isn't much compression from the 3rd cylinder. It's not overheating just idles like crap and puffs a bit of smoke. If I keep driving this with out it overheating and not getting much coolant in the oil am I going to mess it up. Could it still warp the heads since there's no overheating? Probably a stupid question but I kinda need to drive it unfortunately.

 

Its only gonna get worse. Could last a week, or a mile. Hard to say. Keep in mind that you are gonna be applying different stresses on the head as only 3 cylinders will heat cycle like normal.

 

Any coolant in the oil will damage the lower end, even if it ain't much.