major oil loss without drips or smoke

[USSEnterprise]

I'm confused...

I recently went on a longish trip, so I checked my fluids. I didn't think too much of the oil being down a quart since I do have leaking valve cover gaskets and it was almost 5k miles since the last oil change (time to change the oil.)
I topped off the oil and went on the trip, which was about 100 miles round. When I got back, I check the oil and there was only a small drop on the end of the dipstick. I added 2 quarts of oil.

Based on keeping an eye on it, it seems to be using a quart of oil every 50 miles or so. Thing is, there's no spots on the driveway, no smell, and no smoke. WTF?

Does the catalytic converter clean up the exhaust so well that I am not noticing smoke? Really confused...:ybrick:

 

[Doc2012]

Check your coolant. You could have a bad head gasket and the oil is mixing with your water.

 

[BlackCat914]

As a former GM tech and Service Advisor, our 5.3's with Active Fuel Management had a tendency to consume enormous amounts of oil. Sometime 1.5 or 2 quarts in 1,000 miles. In those instances, you would not see any smoke out of the tailpipe. If your truck was, in fact, using 1qt of oil every 50 miles, your plugs would be so fouled I doubt the truck would even run. I'd look a bit harder elsewhere.

 

[Forrrrest]

Well you did just said you have leaking valve covers......

 

[BlackCat914]

Well you did just said you have leaking valve covers......

You know how big of a smoke show that would be? A quart in 50 miles is A LOT of oil, either leaking externally or using it. If the valve covers were leaking that much oil, there'd be oil EVERYWHERE.

 

[LittleCaesar]

Check to make sure the PCV rattles. For $10, replace it with another OEM one.

Also check to see if there is oil in the intake. You may have some major blowby happening.

 

[Forrrrest]

Ya I know that, but it could be a multitude of different things! Start with the problem that you know is evident and continue from there. X2 on pcv if you replace that be sure to get the grommet with it!

 

[mmml4]

I have a Mitsubishi pu and several years ago it was using a lot of oil and like yours no big leaks or smoking. I replaced the valve stem seals and the loss was cut in half. Just a thought.