Major oil loss

[Maximus1]

I’m sure this has been discussed before but I wanted to start a new post because my situation I believe is unique.
2004 Tahoe 5.3L with CNC ported 799 heads
Ok so I just changed my oil approximately 500 miles ago. So I’m planning on driving a total of 4 hours tomorrow so I decided to give the Tahoe a once over and I noticed I was low on engine oil. It ended up taking 4 QUARTS. It doesn’t smoke and there is no leaking underneath. I would’ve thought that if I lost that much oil to burn off it would be smoking. Anyone have any ideas? It’s full now and I’m traveling approximately 400 miles to and from tomorrow and I will check it again and probably several times in between. I’m just at a total loss. Where the hell is this oil going? I’ve actually considered that someone drained part of it. (Yeah I know I sound crazy) but seriously I considered that someone is draining it what else could it be losing that much oil? The Tahoe is at 85% as of tonight along with 4 new quarts of mobile 1 5w-30. Thoughts?

 

[Tonyrodz]

I’m sure this has been discussed before but I wanted to start a new post because my situation I believe is unique.
2004 Tahoe 5.3L with CNC ported 799 heads
Ok so I just changed my oil approximately 500 miles ago. So I’m planning on driving a total of 4 hours tomorrow so I decided to give the Tahoe a once over and I noticed I was low on engine oil. It ended up taking 4 QUARTS. It doesn’t smoke and there is no leaking underneath. I would’ve thought that if I lost that much oil to burn off it would be smoking. Anyone have any ideas? It’s full now and I’m traveling approximately 400 miles to and from tomorrow and I will check it again and probably several times in between. I’m just at a total loss. Where the hell is this oil going? I’ve actually considered that someone drained part of it. (Yeah I know I sound crazy) but seriously I considered that someone is draining it what else could it be losing that much oil? The Tahoe is at 85% as of tonight along with 4 new quarts of mobile 1 5w-30. Thoughts?

Damn, so it was running with only 2 qts? Super lucky. Sorry I don't have any helpful info, I hope you figure it out. How's it running? How was your oil pressure? Low? Normal? Just for the hell of it--have you checked your plugs for fouling? Pcv clogged? Just throwing out ideas.

 

[Maximus1]

Damn, so it was running with only 2 qts? Super lucky. Sorry I don't have any helpful info, I hope you figure it out. How's it running? How was your oil pressure? Low? Normal? Just for the hell of it--have you checked your plugs for fouling? Pcv clogged? Just throwing out ideas.

Yeah I know I avoided a major problem.Oil pressure is nearly 40 psi at idle. It’s running fine. I haven’t checked the plugs yet but that’s a good idea. I’ve never changed the pvc. I believe it’s built in to the valve cover. You think maybe that’s where it’s going? After reading your reply I saw one on summit racing and bought it. The add said that it has a different design on the inside baffles to help with oil consumption.

 

[Doubeleive]

4qts in 500 miles I think you would be either smoking or have a hell of a mess underneath oil doesn't just vanish. years ago when i couldn't rub 2 nickels together I did an oil change, started it up, pulled out of the driveway and saw a huge puddle of oil in the driveway, I was so mad because i was pretty much flat broke and had to go buy more oil, turned out when I removed the old oil filter the gasket from the old filter had stuck on the engine and when I put on the new filter with it's gasket the two gaskets just twisted together and ya big mess

 

[SnowDrifter]

Modern cats burn so hot you won't necessarily even know you're burning oil

Run a compression test, inspect the pcv hoses, and either inspect your pcv valve or pull the drivers side valve cover and look at the integrated pcv valve. Can't remember if all the years have hlthe integrated valve or not. I don't think there's a check valve on the intake portion of the pcv system so I dont think it would be building pressure unless by some u holy miracle both orifices were plugged, but it's still worth investigating.


Is this oil consumption a new issue?

When you say there's no oil underneath, do you mean there's no drips on your driveway? Or that your undercarriage is 100 percent dry? It's possible you have a fitting or filter not sealing right and only leaking under pressure, when you're driving down the road.

How's your coolant?

 

[swathdiver]

Do those trucks have the external engine oil cooler? I've had those lines burst on me twice over the years.

 

[afpj]

Iirc only the 2500 with heavy duty tow package have the factory oil cooler.

Wonder if just forgot to put in enough oil at oil change? That would be something I’d do if I was task saturated, which happens more as I get older. Like snowdrifter said, is the carriage dry? No drip? Unfortunately I’ve had recent need to use UV dye... at that potential consumption rate you’d get a trail running down the block somewhere just driving down the street and back.

 

[Maximus1]

Iirc only the 2500 with heavy duty tow package have the factory oil cooler.

Wonder if just forgot to put in enough oil at oil change? That would be something I’d do if I was task saturated, which happens more as I get older. Like snowdrifter said, is the carriage dry? No drip? Unfortunately I’ve had recent need to use UV dye... at that potential consumption rate you’d get a trail running down the block somewhere just driving down the street and back.

actually I buy the 5quart jug + 1 quart to keep this from happening

 

[Maximus1]

Modern cats burn so hot you won't necessarily even know you're burning oil

Run a compression test, inspect the pcv hoses, and either inspect your pcv valve or pull the drivers side valve cover and look at the integrated pcv valve. Can't remember if all the years have hlthe integrated valve or not. I don't think there's a check valve on the intake portion of the pcv system so I dont think it would be building pressure unless by some u holy miracle both orifices were plugged, but it's still worth investigating.


Is this oil consumption a new issue?

When you say there's no oil underneath, do you mean there's no drips on your driveway? Or that your undercarriage is 100 percent dry? It's possible you have a fitting or filter not sealing right and only leaking under pressure, when you're driving down the road.

How's your coolant?

Coolant is good. Compression is an average of about 185 per cylinder. The oil filter is a good idea but like others have said that the underside would be coated in oil. Just to show that I’m not bullshitting here is a picture of the underside of the Tahoe. I honestly think it’s either going out the Pcv (the reason I just spent $65 on a valve cover) or someone is screwing with me at the shop.

 

[Maximus1]

And yes that’s a new built transmission. 4L70E. 5 plantary gear sets corvette servo bigger boost valve and a high performance Sonnax output shaft since the last build I blew out the output shaft on launching. I guess too much weight to horsepower