My shiny 97 Laramie will go 1000 miles on a fresh oil change including STP then it is down a quart. After that it is 300-500 then down a quart, really down. Had my wrench guy look @ it he thought probably it had gotten dirt in it @ some time before I got it. It has 180,000 on it. Oh, I can live w/ oil usage, but why so much after 1000 miles? Both my Laramie 318s oil gets black quickly.
Now, the other one will go 4500 miles before it goes down. Once, when I was a County Commissioner, we were @ a finance meeting; one guy complained he had just run his new 5.3 GM out of oil, another said they just got a new 5.3, the other 5.3 was being tested as we @ the meeting. I of course said "my 97 Laramie w/ 220,000 had consumption problems too, it uses a quart in 4500 miles."
MY QUESTION WHY THE HEAVY OIL USAGE AFTER 1000 MILES?

 

The oil breaks down over time....

Have you fixed your plenum? Got any leaks? Done a compression test?

 

How is that PCV valve doing? pull the line off and see if there is oil in it. I replaced the plenum gasket and pan in my truck then a while after that I changed the whole intake manifold. When I took the pan off the bottom of my old manifold I saw a nice splatter of oil where the PCV valve connects.

 

Do you think oil should break down after 1000 mi on a fuel injected auto?

 

It isn't completely broken down, but, it is on its way. Plus, it will pick up contaminants from blowby.... not to mention the old oil that doesn't come out with the oil change.

 

A lot of the oil I go through can be found in the catch-can... certainly not all, but at least half of it... and I have a new factory PCV value (aftermarket are worse).
I was surprised at what I was catching... not that it was through the PCV valve, but that it wasn't passed the rings.
I do a half quart every 2,000 on a 194k engine.

[edit]
I use full synthetic oil, changed between 5,000 and 7,500 miles.

 

Tried thicker weight? I switched to 15w40 back in about 2005 because it used oil so bad. In fact, had the plenum switched because it used oil so bad. The plenum was perfectly intact. That was about 65k on it. Now I have 195K+ and still going. The thicker oil helped, but in 2011 I changed to 10w40 maxlife and I like that a lot better.

It got to the point I would put five quarts in and add 1 over a period of a couple months. When that 6th quart was at "add", it was time to change. That equaled about 3k or 3 months. So technically, it burns 2 quarts.

I also learned about Mopar PCV valves way back too. Recently, I had to add two quarts so I grabbed a new PCV. Went back to using one. Some of it is the emission controls, some of it is just my engines build tolerances, some of it is age. Oh, well. Gives me a chance to check the oil once a week and get that great smell on my fingers for a while.

 

Thank you for the info, I'd been adding Mobil special but bought a case of Havoline both 10-30 Maybe I'll take it back for 10 or 14-40. Check the PCV but I think it was checked. I bought it 2 years ago cheap best job of jewing in my life, just had a feeling about the engine, bought it anyway because of the body. Would have even paid his price but I went for the throat. 160,000 then

 

The thought of "checking" a PCV valve to see if it is good by shaking it and hearing the rattle is not accurate. PCV valves are really complex little gizmos. They have teeny springs and parts and will still rattle when bad. The check valve has to close and open at particular pressures/vacuums thus a rattling valve may still be bad. That's how I discovered non-Mopar valves are junk. Rather, go by the age. If you know it is over 3 years old, I would change it with a Mopar one. Case in point is my new one. I hadn't changed it over six years and forgot about it. It rattled and I thought it was good. Then I thought real hard and remembered they have a life span. Changed it and saved a quart of oil that last change.

 

With a catch-can, you can monitor what you're trapping... when it increases with any significance, time for a new PCV valve.