Chevy Silverado and GMC Sierra Forum banner
1 - 19 of 19 Posts

· Registered
Joined
·
32 Posts
Discussion Starter · #1 ·
Hello. I have a 2007 gmc sierra 1500 crew cab with a 5.3 motor. I have milky engine oil with no engine coolant being used. I have suspected an issue with pcv i have diconected the system and just vented the gases and did an oil change with flush. Same result after about 1 month. Milky oil.

Did anyone ever have a simular situtation or have any idea on how to fix it ?

Any help greatly apriciated.
 

· Registered
Joined
·
572 Posts
Most if not all vehicles with modern PVC system will develop some of this as the temperatures get cooler. Most folks notice it on the underside of the fill cap or inside the valve covers. The water comes from condensation inside the engine.

Where are you seeing this? With the vehicle completely warm after a long cruise? I don't consider the normal "milky oil" in the valve covers an issue to be concerned about.
 

· Member Extraordinaire, Servicemen, How-To Author
Joined
·
17,133 Posts
What does the oil look like when you drain it for an oil change?
 

· Member Extraordinaire, Servicemen, How-To Author
Joined
·
17,133 Posts
Sounds like coolant to me. Condensation seems unlikely unless the truck is driven just a few miles each time and then it usually doesn't show up in the oil drain to that extent.
 

· Registered
Joined
·
554 Posts
We can get some condensation up here with weather changes, but that sounds like more than a little bit. Could be a leaky gasket, is your exhaust clear or showing a little smoke? I'd put the PVC system back together unless you already have, that will help to vent the crankcase. Also, if you have been driving just short trips, maybe a long trip to really heat up the system and burn some moisture off. If there is a leak, that should be easier to measure too.
 

· Member Extraordinaire, Servicemen, How-To Author
Joined
·
17,133 Posts
I think I remember a post some time back where one guy recommended a long drive followed by removing the oil fill cap to let the moisture in the oil dissipate. I don't remember if this is just an occasional thing or something to do often. But try to stay away from those short drives, especially in the cooler weather.
Still, I agree that it is more likely a problem with a gasket or or something else that is letting coolant in.
 

· Registered
Joined
·
382 Posts
esox07 said:
...try to stay away from those short drives, especially in the cooler weather.
I don't mean to high-jack a thread, but I've always assumed that if you were driving long enough for the coolant temp to get up to normal operating temp, then you were fine. Just out of curiosity, how far would you guys say you'd have to go to get out of the 'short drive' zone? Would you agree with my logic?
 

· Banned
Joined
·
2,175 Posts
Id say that's about right normally to vaporize if you don't have a leak anywhere. Whether or not it comes out is a different story but no more should go in either if its not going out. O-ring etc. Being sealed I don't see how very much moisture is going to get inside the engine. Very minimal.
 

· Registered
Joined
·
122 Posts
Where are you checking the coolant level, just in the overflow bottle or did you pop the cap and look in the radiator?
I have seen coolant recovery systems not working correctly and the bottle was full but the radiator was nearly empty.

Check it cold.

The radiator should be completely full with little to no air in it.

As was mentioned once the water is in the oil a good long run will not get the water out of the oil, but heating the engine up good will get the water out of the engine before it can condense and get into the oil.
Just running till the coolant is up to temp is NOT getting the engine warmed up fully, It can take as much as 15 to 20 minutes of normal city driving to fully heat things up a bit faster on the highway or under a heavier load.
My truck is blowing hot air in 1 mile at 30 MPH, at that point the oil is still cold.
 

· Registered
Joined
·
554 Posts
For sure, the only way to be sure of the actual coolant level is to check the radiator level, but wait until the engine is cool to avoid a burn. I don't know if the road trip itself will drive the milky colour out of the oil once its discoloured. You may have to drain it out. If your oil has been churned enough to become foamy, it may be too thin to circulate properly and you may end up with overheating issues. Another way to check is after the engine cools, drain a small amount from the oil pan drain plug into a clear plastic bottle or glass jar. Water is heavier than oil, so you may see engine coolant sitting under the oil.
Hopefully you just have a bad head gasket, but a warped cylinder head is also likely.
 
1 - 19 of 19 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top