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

 

[Maximus1]

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

Not mine but it does have a power steering cooler and a transmission cooler

 

[Maximus1]

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

Yeah me too. But I would’ve noticed it when I backed out. I’m at a total loss on this and I really need to figure out where this oil is going. I use only Mobile one so it’s really expensive for an adding a extra 4 quarts. I just got back from about a 400 mile trip for Thanksgiving day and really nervous checking the oil at every stop and no loss whatsoever. This really just started or I should say this is the first time that I’ve noticed but I’m a mechanic and a performance engine builder for the last 23 years so I’d say that I check my fluids more often than most people. I’m hoping that the new valve cover will fix it if this is the problem. I’m just starting to get confused because I just drove 400 miles without a drop missing. Now the 500 miles is just an estimate but when I noticed the oil low the oil change percentage was at 85% so whatever that converts into mileage. If I find out that it’s someone at the shop they’re likely to get a serious ass whooping because I have thousands of dollars and several hours of labor invested in performance parts on this engine. Basically everything that you can do to an engine minus nitrous or a turbo or supercharger has been done to this engine. I’m estimating that it’s putting out close to 500 horsepower at the crankshaft ( based on a HPP program that convert cubic air movement and rpms into horsepower) I am going to put it on a dyno just out of curiosity. and I recently ran a 12.1 in the 1/4 mile. So yeah they would get a serious ass kicking.

 

[Maximus1]

Here’s a video of what my Tahoe sounds like after we finally got it tuned correctly. Took about 5 hours to tune.

 

[Maximus1]

Here’s the plug out of cylinder 1.

 

[swathdiver]

I’m estimating that it’s putting out close to 500 horsepower at the crankshaft ( based on a HPP program that convert cubic air movement and rpms into horsepower) I am going to put it on a dyno just out of curiosity. and I recently ran a 12.1 in the 1/4 mile. So yeah they would get a serious ass kicking.

Use your race weight and speed through the traps in the 1/4 mile to calculate true Rear Wheel Horsepower.

Tom, the motor sounds great, did you post a build thread? Hope the oil thing is an anomaly. One of our Pontiacs would mysteriously consume all of its oil once every couple of years. Only thing that made sense was that all the piston ring gaps lined up.

 

[CAPTAINJAMES47]

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?

I have had the same problem, stopped in to my GMC dealer had the truck (2008 Yukon) serviced left next day for a trip up north from FL while driving up in the smoky mountains alarms went off no oil pressure etc. Shut off engine pulled off the freeway checked oil. nothing on dip stick. put in 5 quarts. (thank God I had it in the truck) drove to next exit to our hotel everything went fine no damage. next morning checked oil it had the 5 quarts in and right on the full mark. Drove to WI from FL and home and it used just one quart about 1200 miles. Then this last month we drove out to Phoenix from FL almost the same thing happened after about 1800 hard miles 80 mph and above pulled in for the night got up the extra morning after letting the truck sit all night and I was down 3 quarts of oil. Filled it up and left everything went well check oil every time we stopped for gas and it only used 1 quart for about 1200 miles after that. Total trip of 5264 miles used 6 qt oil which included the 3 I put in at one time. I have no idea where it goes but now I check the oil every time I get fuel without fail.

 

[SMonaldo]

I have an '07 Trailblazer, 208K on the odometer, and from day one have been using Full synthetic oil, until recently. I am in fact using an average of 2-4 qts. of oil in between changes. My mechanic has said basically these engines are notorious for burning oil as mileage increases, a lot of "slop" develops internally. His recommendation is to switch to the semi-synthetic blend, as it is better (and cheaper to refill). He feels that the synthetic is too thin for the slop and hence gets past the rings. I have only just done this with my last change, and while it still burns the oil, it was cheaper to refill, and cheaper than a major engine overhaul.....hell, my '07 Impala SS (305-8CYL) was burning oil at 90K, so I am not surprised by my Trailblazer.......maybe GM needs to look a little deeper at these issues long term.....