Oil in coolant resivor
 

1999 Dodge Ram 1500 4x4 5.8 magnum finding a layer of oil sitting in top of my coolant in the resivor. Not sure if this is a plenum related issue cause it also needs that to be replaced or if this could be a head gasket. Any info helps

I am not entirely sure how oil could manage to find it's way into the coolant...... Cooling system is pressurized, and doesn't even come close to pressurized oil anywhere in the engine...... Think I would be tempted to flush the cooling system really well, and see if any shows back up. I have no clue how it would get in there in the first place.

Sounds like the head gasket is blown. Rent a block tester. Should be pretty much free, once you take it back.

Are you sure it's not transmission fluid? The cooler built into the radiator can go bad and leak.

I noticed it while flushing my whole system and looked over and saw it was in there. Going to have to test it

Is it the first flush you've done? Could be magic chemicals (stop-leak) introduced earlier in the truck's life. A quick check, if the system is drained, is to swab the bottom of the inside of the radiator through the lower hose port -- if you get goo, you've got work to do.

Actually just bought the truck a few days ago so now I'm really playing catch up and finding out what needs to be replaced and al that . However it did have a new radiator and the coolant was a dark orange so that's a sign to me that there was a good amount of stop leak used in the past which led me to the major flush I did. Haven't seen oil in it since but I will check this weekend to know for sure

You also said in your other thread that you were having problems with shifting, it should be a no brainer but if you haven't checked the fluid level hot, then go ahead and do that. If enough tranny fluid would leak out, then that would cause shifting issues.

Yeah checked the tranny fluid hot once already and it seemed to be at the correct level but there were a lot of bubbles on the dip stick it that means anything. Also took a good look underneath and the transmission seems to have no visible leaks

Did you check fluid level in neutral? If you check it in park, you get an artificially high reading.