Coolant Mixed with Oil!! Help!!!

I own a 1990 GMC Sierra 3/4 (2500) ton pickup. I recently had a slight oil leak, which was caused by the oil cooler lines resting on the frame of the pickup (ive heard that this is a common problem) so i replaced them. I also replaced the radiator, so I have a new one of those as well. Going down the highway the next day, I blew out all of my oil while driving, I was however very quick to pull over and shut it off. This was caused by not fully inserting the quick connecting lines into my oil filter housing. After fixing that problem, I have noticed while checking my dipstick that my oil is a green color. I have no coolant, or oil leaks, but I hear that it might be a blown head gasket, is this correct? My exhaust does not smoke, and there is no "milky" residue on the dipstick, just green colored oil. Help!

check your antifreeze, because of the pressure differences you would most likely have oil in the antifreeze. (oil - 20-60psi, coolant - 15psi) Change the oil and run it and see what it does in a day or 2

antifreeze is a good color, right now i'm just in the "sit and wait" stage, checking my coolant level and oil level very carefully, to see if coolant is leaking into my oil, which would cause my dipstick to look even fuller. the engine is running strong, and my pressures are all good. my next idea is to plug the oil cooler lines just to see if maybe the coolant stops there. but like you said with the pressure differences, that might not make much sense

Intake gasket leaking?

not to my knowledge. just changed the oil again for like the 4th time. I am determined to find out what it is other than a head or intake gasket. I did however notice while inspecting those damn oil cooler lines that the o-rings are pretty much destroyed, making me wonder if any leaks can happen there. i put some new ones on, we'll see.

what oil did you use because some types of oil look green , like castrol racing oil is green

I am using nothing but vavoline 10W-30 motor oil. I've never seen it turn a green color before.

just checking
when you pull the dip stick to check oil level is there little bubbles like water mixed with the oil and is the oil have a cream mixture to it??
pull the spark plugs 1 at a time and see if any look pure white a pure white plug could be a coolant leak in the cylinder

also any sweet smell while the engine is running or any smoke out of the exhaust at any time

no bubbles, no milky color, but i did check one plug on each side, closest to me, and they did have a white color to them. I need to check the others to see if the same thing applies. does this indicate an immidiate cause, such as the head gasket? and as stupid as it sounds i have smelled the exhaust, and no sweet smell. Thanks for your replies

a white plug with a slight tan color is a good clean sign, a brite pure white wit a hint of green would be bad. also with no smell in the exhaust i would say the head gaskets are ok, do you use any oil additives that could change the color of the oil??
you checked the rad and its full of antifreeze??
i cant remember but does you engine oil cooler lines go to the engine rad??

No oil additives have been added to my engine at all. The radiator is brand new, replaced when I replaced the oil cooler lines. The radiator does have the oil cooler and transmision cooler built in. My levels are great as well. The strangest part, I have noticed almost no coolant usage, I even made a mark on the resevoir and nothing has changed, but yet my oil changes to a slight green. I did replace the o-rings with some better ones last night, i'm still waiting to see......

Dont go by the coolant overflow bottle , take the cap off of the rad and check coolant level/ did you have this problem before you changed rads??? if not the new rad could have a pin hole leak inside the oil cooler

I did have the same problem with the old radiator, which is part of the reason i replaced it, plus i had a leak. The level in the radiator itself is good too. Anytime i check the level in the reservoir, i check under the cap also. I am just completely stumped. I plan on checking all spark plugs this weekend for more evidence of coolant leaking. I have also been playing close attention to the oil level, if it was rising, i would know that another liquid was getting in somehow.

what gets me is any time water/antifreeze enters into the oil system it turns the oil to a milky color. You say it has no milky color, no loss of antifreeze, no change in oil level, no smells of any kind and it runs just fine
the oil lines leaking have nothing to do with antifreeze in the oil
you have to be missing something or you are joking with us

I am in no way joking. I wish i had a consistant sign of symptoms which would lead me to believe what the problem really was. I have put so much money into this pickup already, including an engine rebuild. At this point, i wish the oil was a milky color, but it is a green color. Right now i'm just driving the vehicle watching closly for changes. the engine is running strong still, no knocks, no studdering, no smoke.

how long ago did you get it rebuilt and when did the oil color change start

I had it rebuilt about 2 years ago, maybe even three. it's a 1990 and only has 125,000 total miles on it, i had the engine rebuilt at 75,000 because i bought it from a guy and the truck sat for a long period of time.

Alright guys, I'm going to give you and update. The coolant is still in my oil, i've been changing the oil on the weekends, I just got back from the L.A.S. and spent $150 bucks on all the gaskets, sealants, and fluids to take the engine apart and replace the head gaskets and intake manifold gasket. I'll let you know how it goes after this weekend. Everyone keep your fingers crossed that this solves my problem.

Just to give everyone an update. Changed the headgaskets and intake manifold gaskets. The driver's side head gasket did have a small spot, which explains my coolant mixed with oil problem. The intake gasket did look good. This project took 19 hours straight to complete. So anyone looking to do this better have a good two days to spare. Been driving my pickup with no problem other than the rocker arms needing a slight adjustment. No coolant in the oil, now i'm selling my truck, anyone want a 1990 GMC 2500 with 126k miles?

Iwant to resurrect this thread

before I go puling things apart, I'm trying to figure if the intake manifold gasket leaking would enable coolant to run into the cylinders? I've got coolant in the oil and excess water coming out of the exhaust.

if its the IMG, I've done this before.

if its the HeadGasket, I'm not sure I want to pull the heads without some coaching.

What is the basic procedure for replacing the head gaskets?

The way I saw it, I just figured that removing all of the things just to get to the IMG, I might as well had removed the Head Gaskets. There was nothing wrong with the IMG, but it is necessary to remove and replace it when replacing the head gaskets. The head gasket was the problem and replacing them wasn't hard, just time consuming. I don't know how most people do it, but I cleaned the head gasket surfaces very well before putting them back on. The truck was running great after all of the replacements.......but I did sell the pickup about a month later. (The gas prices were killing me). If you have any questions, I can try my best to help you out. Give me a shout at [email protected]