Here we go...loosing coolant

I have read over the forum...and I understand that his can be a multitude of things but here goes...

My wife drove out of town the other day, about an hour and a half drive. When she got back home she got about a mile from pulling in and was stopped at a stop light. She said the temp light came on and the needle was at H....she turned off the car. When the light turned green and she started driving the light wasn't on and the temperature stayed around half way. Next stop light it creeped up a little, but never got up that high again. She called me and when I got home I checked the coolant levels. I had the coolant flushed back in June or so...so it was full then and bled. I had to add 2 quarts of coolant. I checked the dipstick that night and it was clean and at the normal level. I went out yesterday and bought a new radiator cap and installed it this morning. I again had to add some coolant, but not as much and also had to top off the resevoir again. This time I checked the oil again..still clean and at the right level. I took off the oil cap and there was milky white sludge on it. Stuck my finger in there and there was some in there. NOW this is the first time I have taken off the oil cap myself. I have never changed the oil in this van myself as I have had her have Wal-Mart do it. Only had the van since May or so anyway. So that could have been there...could have NOT been there as I know the IMG has been done before we bought it. SO...that is where I am...I notice no coolant on the driveway so the coolant is going SOMEWHERE...my question is...Intake Manifold or Head gasket.....

That milky white sludge under the oil cap is a typical byproduct of engines that see a lot of short trips. It's residue from condensation and blow-by gases that get boiled out of the oil when it heats up, on longer trips. This is pretty normal and nothing to worry about. As you suggest, the important thing is to make sure the oil itself is not milky or contaminated.

Before anticipating the worst, I would suggest have a mechanic do a pressure leak-down test on the cooling system to see if its leaking, and, if possible, let us know the results.

If its not leaking, change the thermostat and continue to drive it while monitoring the temp and oil condition.
They are cheap to change and do not last forever. It may be sticking closed, allowing the engine to overheat and boil off some coolant.
This should have been done when the system was flushed, as periodic replacement when the coolant is changed is a good preventive measure.

THANKS! I got in contact with my mechanic today and he said basically the same thing...that if the dipstick is clean like I said it is most likely something else. He wants to do an oil change on it to make sure, then look at the other things...most likely the fans and/or thermostat. When he flushed it some gunk came out so it might be causing the thermostat to stick....getting it to him on Wednesday and will report back what it is...

Just got word from my mechanic....relay. ONE of the relays was bad and evidently if this particular one is bad...the fans don't turn on at all if the AC is off. The other ones are futher down the line and failed when the one went. Fixed it and the fans come on when they are supposed to now. I guess I lost coolant from it boiling over into the overflow tank. ANYWHO...all is well.