Please help if you can... I noticed it a couple months ago when I checked my radiator. The truck has 170,000 miles by the way and is automatic. There was a lot of sludge under radiator cap and around the filler neck. Unfortunately it was low so I didn't see the actual water/coolant level. I'm not really mechanically inclined but I'm ok. My friend was with me and we decided to drain the radiator and flush. (Keep in mind, I've never had an issue with overheating, ever, and I live in Florida). When we took the plug out at bottom... Nothing came out!!!.. There was so much sludge I had to force it out with a hose and a lot of sludge came out. We flushed it out really good and refilled. Today, I realized there is more sludge under cap and floating particles of sludge while cold obviously. I'm confused because back then and today I checked trans fluid and both times nice and pink and no bubbles or anything else. Yes my oil is always low and I have to keep adding due to an oil leak so it is hard to pinpoint how much loss is due to what. However, the oil is not milky and looks nice and clear with no water. I've read about head gaskets, head cracks, etc. The truck runs and drives great for the last 4 yrs I've owned it. No overheating or smoke. My uncle said to try K&W Block Seal in the radiator after flushing to try to stop oil leak into radiator. Truck runs great as i said but I'm afraid If I do the wrong thing or fail to do anything I might have a major problem. I plan to flush again tomorrow but I am hoping one of you guys has some insight... Thanks so much... Jason.(Spring Hill, FL)

 

When you flushed it did you just flush the radiator or did you back flush the entire system. The second round of crud could be out of the block.

Are you sure the crud is oil?

 

I'm not sure about the back flush. I ran the truck for a while and running water through it the whole time. As far as whether it is oil or not??? Not sure.. What else could it be, if not transmission fluid (pretty sure it's not, but?) or oil? Please advise. Thanks