I have a chevy van with a 5.7L V8. I recently took off the lower cooler line on the radiator on the driver’s side and brown oil/sludge dripped out. I checked the oil dipstick and the oil looked normal/clean. I did some research and apparently this could be due to a bad oil cooler causing oil and coolant to mix, and the oil cooler could be near the oil filter. I drained the coolant and it was normal and the coolant cap didn’t have anything on there. Although I do have an intake gasket leak so I lose some coolant occasionally. The engine oil dipstick and tranny fluid all looked normal. I didn’t see one of those tiny radiator oil coolers near my radiator. Does this mean I might have to replace my radiator? Is there a reason why the oil in those lines is different than the dipstick? The oil and filter were changed about 2000 miles ago. Does anyone have experience with replacing this oil cooler or have the part number?
The oil cooler in your radiator is the TRANSMISSION oil cooler.
Take both oil cooler lines off and pressure test your radiator. If coolant comes out where the lines were, get a radiator made for an automatic van and get yout transmission fluid flushed or exchanged.
I don’t think I have a separate transmission cooler. The cooler lines all go into the one big radiator. The line that I took off was on the driver’s side and it goes to the engine. Just to be sure I took off the cooler line on the passenger side and clean tranny fluid came out. I did some more research and apparently for some chevy engines there is an oil cooler for that bolts onto the engine block. The oil filter then screws onto this oil cooler.
Some people said that these lines were prone to leaking and the oil cooler isn’t needed, so they did an “oil cooler delete”. I am beginning to suspect that the previous owner did this, and so the lines aren’t actually being used, and thus the brown sludge that dripped out is just old engine oil left in the lines.
So my understanding is that engine oil doesn’t need to go through the radiator at all, but the transmission fluid needs to because coolant doesn’t go to the transmission?
More than like the lower intake gaskets are deteriorating, causing coolant to get into the crankcase
We have tons of GM vehicles in our fleet
This is an extremely common problem
With all due regard, you need to stop listening to those guys and crawl under the van and find out for sure. More than likely, all the cooler lines are connected and you need to reseal that intake
But look on the bright side . . . because you have a van with a doghouse, it’ll be easier to reindex the distributor and lay those beads of rtv that goes between the two intake gaskets 