2007 Suburban LTZ, 5.3 with 225k.
I know, 225k, what do I expect? Blue smoke and a quart of oil every 500 miles is normal for a 5.3 with AFM and that many miles. Either deal with it or put in a rebuild.
This is probably what I'm facing to be realistic. It doesn't owe me a thing, but I don't want to throw the towel in quite yet. It runs great and is as reliable as the day is long. And I'm not ready to shell out $85k for a new one, or $35k for a used one.
Many mechanics will say that my rings are shot. I don't think so. It doesn't smoke during normal operation, on heavy acceleration, or after a long idle. No fouled plugs.
Some will say that replacing valve seals will fix the issue. Maybe. Can't quite rule that out, but these 5.3 have a unique issue related to the AFM, PCV, oil passages and valve cover design.
I'm putting my chips on a combination of three things:

• 200k miles driven with an active AFM (not disabled) - creating the oil splash/PCV and gummed up ring issues
• 150K miles driven with manufacturer recommended oil change intervals averaging 7k miles (onboard computer) - allowing deposits to build up, clogging screens and passages
• 150k miles driven using conventional oil - allowing deposits to build up, clogging screens and passages

50k miles ago, I started to change the oil more frequently (every 5k), used a quality filter, ran Risolene 100 miles before every change and used full synthetic or synth. blend. I also changed the tiny screen between the crankcase and the oil pressure sensor. This stopped the false low oil pressure readings. I've been using a Range for the last 15k or so, but I think that's closing the barn door after the horse got out.
I'm looking closely at the PVC system and the valve cover update as possibly being a cure - or something that might lessen the consumption issue.
I'm also paying a lot of attention to this bulletin and the subsequent comments.
Any thoughts?
Experiences?

 

Do a compression test, that will tell you if it is rings. Certainly could be valve seals.

 

Compression test will tell if its the rings or valve seals. Bad compression means some air is escaping somewhere instead of being compressed.

This is how we did it years ago (not sure if it will cause any harm on today's engines):

Check compression readings on each cylinder. Then add a teaspoon of oil into cylinder through spark plug hole. Do compression test again. If rings are bad the oil will temporarily seal them and show better compression. If compression is not better after oil, then rings are ok.

Usually smoke on startup was bad valve seals because oil inside the valve covers would slowly seep into the combustion chamber as the engine sat. With AFM, oil may be taking another route.

Steve

 

500 miles and needing 1 qt of oil is pretty bad. My 07 Tahoe has ~265K miles on it, and before I disabled the AFM with the Range device, I was burning oil about 1qt per 1500 miles, after I used the AFM disabler device, it essentially doubled that to 1 qt/3400 miles. I recently had my oil pan gasket replaced and had the AFM oil splash shield put in, and unfortunately it doesn't seemed to have helped any, but I still need more data to really confirm that statement.

If you're not ready to give the car up, I'd say try getting the AFM disabled there are a few options out there. And see how that helps. But my uneducated guess is that piston rings would need replacing for the amount of oil consumption you are having.

edit: i just re-read your post, lol, I see you are using a range device. So did the device help any?

 

I have a 07 1500 with 230,000 miles. This truck has plenty of power and no major issues. Runs so smooth you can’t feel or hear her running at tragic stops. One day at startup I got a big cloud of smoke that cleared up. This happens after the truck has been sitting. After lots of troubleshooting and research the problem is solved. I replaced the drivers side valve cover with updates. 30 minutes and $130 to replace myself. First startup I got a little smoke and after that she is back to normal again. Good luck.

 

Tomcat, I had seen others who had eliminated or substantially reduced 5.3L oil consumption under very similar circumstances as ours by updating the driver's side valve cover/pcv.
I'm going to try this as well. Considering how easy the swap is and the cost of the part, it's worth a shot.

 

For less than $75 for the Dorman aftermarket cover (confirmed that it's the updated version), I decided what the hell? The clouds of blue smoke at startup were getting really bad.
I have to admit - I was skeptical. A 12 year old 5.3 that had enabled AFM 80% of its life is going to tired. And it's going to consume oil. Don't expect a fix as simple as replacing a valve cover. But really, could it hurt to try? After warming up, under hard acceleration, moving after idling for an extended period of time - all the things that say tired rings and/or valve seals, it wasn't smoking at all. So maybe there's some validity to this updated cover being a fix.
The proof is in the puddin'

We'll see if the consumption goes down. Given that the blue billows are no longer, I can't imagine how it won't. Worst case, my Suburban will continue to use oil. But now it will be inconspicuous...and I'm good with that.

 

That’s great. I’m glad it worked for you. Great info.

 

I have the Range device installed, also installed a catch can between intake manifold and valve cover PCV, Wow what a difference the can makes of keeping oil vapor from being reintroduced to the combustion process. Unless I am towing or on a extended road trip ,I rarely have to add any oil between changes. 07 5.3l with 153,000.

Just pulled the #1 plug to inspect the other day, and absolutely no oil on it, the Range really works... Have about 65k miles on this #1 cyl plug....

 

Wow. That is one clean engine. I wish I could say mine was half as clean, but I can’t.
I’ve heard nothing But positive feedback when it comes to catch cans and their effectiveness. Could you steer me toward the best thread describing a catch can installation?