In the summer time I started to overheat on the hwy for no apparent reason - Enough Antifreeze, Fans were Blowing, I believe the thermostat was good. When everything cooled down I noticed oil in my antifreeze. I pulled the thermostat and removed the seal on the radiator cap and the system stabilized. I put in a new thermostat only to have the system overheat again. I removed that thermostat, tested it and found out it was fine...opening to specs. One final note, even though the thermostat is out, the temp gauge is right where it should be but I get no heat. Questions: (1) I'm assuming that the oil is either the head gasket or head/block. I'm trying to see if there is some other area that may cause a similar effect (ie.gaskets around the water pump). Also, are these engines known to crack or warp. (2) How can I not have heat, even though my gauge is showing a temp of about 190. Can this be a poor waterpump not flowing the coolant (which may explain why I overheated)...there is no noise or whinning coming from the unit. Sorry for all the details but I've been banging my head on this one.