Hi everyone, I also did post in the general oil forum. I have an 04 Aztek running Pennzoil synthetic. I had blackstone check my oil on the last change and they confirmed coolant in the oil. Anyone familiar with the 3400 engine knows of all the gasket issues with this engine. I've been to the dealer twice regarding this issue and they are disputing that there is anything wrong and they do not see coolant in the oil. The dealer says that an INDEPENDENT lab analysis will not hold up with GM or GMPP(extended warranty)which makes no sense to me. The dealership was looking for some visual signs vs a scientific analysis. They rechecked and could not find a problem. They added a dye to find the leak. I took it in yesterday and again, no problem. Does anyone happen to know if coolant affects synthetic oil differently than conventional? I have been using synthetic. I was curious if it still shows the same symptoms such as white milky consistency and whatever else? I have noted though that since I picked it back up this past Friday, the temperature has been flutuating much more. The needed normally has always held at the normal position just below the half-way mark. Now, when I've been at a stop for a short period of time or idiling, the gauge rises above the hlf-way mark and towards the mark in between half and hot. I am not sure if during their "testing" such as a pressue test if it affected the thermostat or another sensing unit? By the way, the coolant resovoir is full to normal level.