Transmission Fluid or Engine Oil?

[cchase]

This is on a 2002 Chevy Malibu with the 3.1 V6.

Recently ran a used oil analysis on the oil because I had my suspicions about the LIM gasket at 83,000 miles. Blackstone picked up 114ppm K and 28ppm Na on Pennzoil Conventional at 4,331 miles on the OCI, enough for them to go Pos on coolant, Tr on Water and highlight coolant in the oil with the LIM gasket the likely culprit on these engines.

Noticed that there is also what appear to be drops of oil on the surface of the coolant overflow tank.

The oil is visually clean (as it was on the tested oil), nothing on the cap, coolant is a little murky but it is overdue to be changed.

Now I am at the point where the leak is too small for it to show up on a pressure test (if the HG or LIMG is suspect).

What I am worried is that the LIMG will be replaced and then I find out it's actually transmission fluid in the coolant, not engine oil.

Thoughts? Ways to approach?

 

[PhillyJoe]

The chances of it being transmission fluid are slim and none.

Could be IMG or HG, can't really tell until you take it apart.
I have a small IMG coolant leak in a 2002 Grand Am 3.4 and the dealer quoted $710 to replace. Add a few more dollars if it's the HG.

 

[Trav]

I doubt its transmission fluid,if the internal transmission cooler were leaking in the radiator there would probably be a lot of flow resulting in a sickly pink colored mess in the coolant or the transmission.
Do the LIM before any damage is done.

 

[willix]

Its not uncommon for trans coolers to contaminate cooling systems from a cracked coil in the radiator tank.

Have you been monitoring the transmission oil level at a consistent temperature.

Headgasket comes to mind maybe intake gasket.

 

[pbm]

The 3.1 and its 3.4 variant are known for leaky L-I-M gaskets and I'd be surprised if it is anything else.

You can add Barsleaks or GM sealing tablets as a stopgap measure until you have the time and $$$ to fix it right. Fixing it right entails a new Felpro Problem Solver gasket and new bolts and a properly done job. Good Luck.

 

[cchase]

Everything said so far agrees with my line of thinking. My suggestion was to just have the LIM gasket replaced. At the very least it should eliminate the coolant in the oil.

If, by some stroke of bad luck, there is also transmission fluid in the radiator, go from there. But my suspicion would be that if there was transmission fluid in the coolant, there would be coolant in the transmission fluid, of which there is not.

 

[onion]

A leaking intake gasket can cause oil in the coolant. As the coolant system cools down, it will sometimes be under a slight vacuum (which is how coolant is sucked back out of the overflow tank... on systems that have one). This slight vacuum can pull a small amount of oil into the cooling system from whatever oil happens to be clinging around the leaky area of the gasket. I've seen it quite a few times.

 

[dwendt44]

The 3.1/3.4 V-6 are pretty stout engines except for the LIM gasket problem.
IF you've never overheated this engine, I doubt it's head gaskets.
The cooling system is under more pressure than the transmission cooler so cross contamination here would put coolant in the T fluid.