2007 Hummer H3 3.7L with 150k

I go through a quart of oil every 1000 (give or take) miles. We use Mobil full synthetic and change the oil every 3000 miles. No smoking that I have noticed and no leaks found. Motor runs and sounds good. Any ideas?

 

Welcome to HF. Check the coolant for contamination.

You truck has the GM Oil Life Monitoring System, you should use it, The change the oil every 3000 miles is now at least two decades removed from reality.

 

Does your truck smoke like blue ? Maybe your cylinder head gasket gone bad? Did you find no oil leak underneath? Bad oil pump ?

 

I haven’t seen any smoke of any color come out of it and it’s my daily driver. No oil under it either. I have a list of things I’m going to check so I’ll add these ideas to it!

 

Well I am concerned that I have a blown head gasket or something else serious with my motor. Just went out and looked at my oil and coolant. Coolant seems to have oil in it (has a brown shiny color) and the reservoir is empty even though we just filled the coolant. Took the oil cap off and have a milky substance right inside. Checked my oil level and it’s about 2/3 down on the dip stick even though we changed the oil only 500 miles ago.

 

Sounds like what you suspect. Take it to a good mechanic for diagnostics and repair.

Its serious so do not delay.

 

 

Your suspicions are well founded. Check the trans fluid level/color as well.