Hello,

VEHICLE INFO:
2012 GC 3.6, 104K, well maintained, used for in-town, extremely short trips (less than 2 miles each, 8 per day), & occasional highway. 99% city, 1% highway.

PROBLEM: I noticed a water-like substance in the old oil during the last oil change. I thought it could be this van's light colored coolant & suspected a head gasket leak, or condensation accumulation from using an oil pan heater during the winter.

TESTING & OBSERVATIONS: Combustion gas leak detector kit was used & fluid stayed blue, so head-gasket ruled out. Did the test from cold to hot, for a while to be sure of results. No frothy milkshake under the oil cap, or on the dipstick.
Another observation, after shutting down the engine hot, the coolant hoses feel non-pressurized after a few minutes. I would expect them to stay pressurized longer??? I just found the watery substance in the oil, so I have not had enough time to observe the coolant reservoir to see if engine is consuming coolant.

SYMPTOMS: No major symptoms. Strange exhaust smell when accelerating hard on highway. No exhaust leaks seem to be present though.

Any thought, or advice would be appreciated.

 

Try renting a cooling system pressure tester. Check the engine cold (after sitting overnight) and hot (obviously you want to remove the cap carefully to prevent flash boiling). Pressurize to the rating on the cap and observe the pressure for 5 minutes - you shouldn’t lose more than 2 PSI, cold or hot. If you do, watch for signs of coolant dripping off the engine. If you don’t see anything, you’ll have to isolate the radiator and block for separate pressure testing to see where you’re losing it.

 

Genius GumbyRT! I knew someone would come through! Thanks for the lead. I'll rent a tester tonight and post the results. Thanks again!

 

I wanted to bring this old thread alive for the DIY'ers, who may not be aware that coolant and oil can mix at the oil cooler, which is located under the intake, due to the oil cooler's seals failing. People seem to be replacing the whole unit, but Mahle has come out with a replacement set of gaskets and the part # is: MAHLEGS33683.
So, you may find oil in your coolant reservior, or may find coolant/water in your next oil change, and if you do, this might be a good palce to check to see if this happened on your 3.6L. I only had water in the coolant once after an oil change, and I belive it was due to using an oil pan heater in the winter and not having any highway miles. I did the coolant pressure test, and a cylinder head test, and it passed both tests.