My truck started blowing smoke at start up a couple of months ago. At first it was just a little puff every now and then, but this morning was different. My girlfriend went to move the truck after it had sat for a few days and it blew out a cloud of smoke the size of a VW Bug. Valve guide seals? It has 234,000 miles so I'm not too surprised, but how much does this cost to fix? Is it even worth it? Should I pawn it off to the next sucker now befor it gets worse or what?