I heard about this site from someone on GM-Trucks.com. That site has been a real help with keeping my truck going and sharing info. I have a 2000 Silverado Ext Cab Z-71 w/5.3. It has about 116K miles on it and I just got done replacing the head gaskets on it because I was using coolant. It had been using a slight amount of coolant for about 2 years but lately had gotten much worse. I discovered it was getting into the oil. When I pulled the head, the top of one head had a lot of black sludge among the valve springs and the under side of the driver's side valve cover was coated with a butterscotch colored slime from oil/water mix. I have been running Mobile 1 for about 30K and ran Castrol GTX before that. When I went to change the oil after the gasket change, I pulled the oil drain plug out and nothing came out! The sludge build up in the pan was so bad, I had to poke a screwdriver up there to get the oil to drain. Not sure where all the sludge came from, except from the water/oil mixing for a while. Hope it isn't the Mobile 1, I've heard all good things about that. I now have an extra 5.3 with about 50K miles on it on the engine stand to go in if I have more problems with mine.

Anyhow, that's my truck and where I'm at on it at the moment. Looking forward to more info and sharing tips!