Oil consumption

[Hammer_95]

What is everyone’s experience with oil consumption on the TBI engines? I have about 137000 original miles and burning about a 1/2 to 3/4 of a quart every 2000. I had a PVC issue that I corrected, no visible leaks bottom is dry as a bone. This is my third one of these trucks and the other two didn’t burn hardly any when I changed them at 3-4000. That was also 20 years ago when I owned them so just the age rather than miles may be against me.

 

[evilunclegrimace]

Valve seal? Intake Leak?

 

[smdk2500]

I wish I could get that far on that much oil usage lol. I'm lucky to get 500 miles to a quart in my 5.7. Many years ago I had a 94 with a 5.7 with about the same mileage and I used about a quart every 3000 miles. I would agree with the above post on what is possibly wrong. But I've been wrong more then I've been right.

 

[fancyTBI]

I third the valve seals and intake gaskets.

Valve seals can be an easy check. Start the truck and watch the exhaust. If there is a puff of blue smoke on startup it is possible that you have failed valve seals.

Does it use more oil under certain driving conditions? For example city versus highway/extended driving.

The symptoms you described are what I had wrong with my ‘95.

 

[SentandBent4x4]

I think it’s possibly be a worn piston ring, letting oil into the cylinder to burn. Is it smoking blue or blackish? Not that that’ll tell the problem, but just curious. I believe if you check the spark plugs then you’ll see burnt oil residue on the plug. You could look up a vid on YouTube on how to tell if a cylinder is burning oil. Best of luck to you!️

 

[SentandBent4x4]

I’m not saying it has to be that, but it definitely could be. Seen it happen a few times.

 

[L31MaxExpress]

I would not expect the tightest of engines to burn less oil. Anybody claiming their engine is not burning a noticeable amount of oil in 2,000+ miles has a crankcase filling with moisture and other contaminates. Oil gets past the moving parts and burns in the combustion chamber. The 350 in my van was perfectly healthy and burned a quart in 2,200 miles on a long, high speed trip. Check the stick regularly, top it off and keep going. Fresh oil will actually burn off lighter hydrocarbons relatively easily, making fresh oil more prone to loss. Up to 1qt every 1,000 miles is perfectly normal in some driving conditions. An engine will burn the most oil under high rpm deceleration, like coasting down a mountain in 3rd gear with a trailer behind you.

 

[Schurkey]

What is everyone’s experience with oil consumption on the TBI engines? I have about 137000 original miles and burning about a 1/2 to 3/4 of a quart every 2000.

There was a time--decades ago--when GM claimed that a quart to 700 miles was "Normal". We all knew that was horseshiit, but that was GM policy.

My '03 Trailblazer with the 4.2L inline six would go 4000+ to a quart. Somewhat less than that, now--but it's got 270K miles on it.

A quart to two thousand miles doesn't seem extreme to me. Less than that is pretty good.

As said--some oils will lose the more-volitile fraction of the petroleum molecules faster than others. Amsoil is good in this regard.

 

[Pinger]

Not a TBI but a Vortec 5.7 with 48,000 miles and it took 0.5l (very close to 0.5qrt) after 4000 miles.
Prior to changing inlet manifold gaskets it was using oil.

 

[SentandBent4x4]

How often should I check my oil? I usually do it every couple months, and it doesn’t seem to change much, but I hardly drive it. Should o check more often?