Oil loss after trans service

Bent GMC · February 19

I decided to get a transmission, service flush, etc. and when I got the truck back two days later, I get a message that engine oil is low, so I check it and sure enough I’m 3 quarts low. I called emailed regarding maybe an apprentice inadvertently drain the wrong fluid. Got no response. Issue I’m having is after I filled my oil back up a month later I had to add two quarts and then a month later which is now adding 3 quarts. I have absolutely no leaks of oil anywhere on this truck so where is this oil going? Is it because of the switch to four-cylinder or because I got a transmission service? I don’t know what the heck is going on, but I’d like some advice.

MikeBMW · February 20

Taking it to another repair shop for a second opinion would be my endeavor.

davester · February 20

check if there's any sign of oil in the engine coolant.

davester · February 20

and maybe pull all the spark plugs and see if any look oil-fouled.

asilverblazer · February 23

Year?

Model?

Engine?

Mileage?

Every engine uses oil (I measure what comes out of the pan at every change on every vehicle - every one of them is usually a quart less than what goes back in. Nissan, Ford, Honda, Chevrolet, Mercedes Benz, turbo, N/A, supercharged, direct injected, carbureted, 3,000 miles 300,000 miles.)

3 quarts a month seems excessive - how many miles are you driving in that three months?

newdude · February 23

On 2/19/2026 at 6:47 PM, Bent GMC said:

I decided to get a transmission, service flush, etc. and when I got the truck back two days later, I get a message that engine oil is low, so I check it and sure enough I’m 3 quarts low. I called emailed regarding maybe an apprentice inadvertently drain the wrong fluid. Got no response. Issue I’m having is after I filled my oil back up a month later I had to add two quarts and then a month later which is now adding 3 quarts. I have absolutely no leaks of oil anywhere on this truck so where is this oil going? Is it because of the switch to four-cylinder or because I got a transmission service? I don’t know what the heck is going on, but I’d like some advice.

If it's not leaking, its burning.

Switch to Valvoline Restore and Protect.

GMCustomerService · March 9

We understand how frustrating troubling oil concerns can be, Bent. This isn't the ownership experience we'd like for you to continue to have and we'd like the opportunity to connect further in an effort to explore ways we can assist. When you can, please email us at [email protected] with your Username and Forums in the subject line to get started. Our team will keep our eyes peeled for your outreach.