Oil consumption

I have a 2002 Avalanche with 81k miles and have never had a problem, other than the “low fuel” light seems to light up too often. However, it had begum to consume 2qts of oil within 2k miles, yet there is no odor, no leaks and no smoke from the exhaust. The dealer, who I trust, wants to perform an “oil consumption test”, which, if like any medical procedure, will likely cost me $$$ with no meaningful prognosis, other than to spend additional mass quantities of $$$. They did have a good suggestion that the issue could be a worn PCV valve. I thought I may follow that course, given the miles on it. Again, the engine runs just fine and the oil pressure gauge doesn’t indicate anything abnormal. The “add oil” warning light does come on at about 2,500 miles after an oil change, though. Thoughts?

Don Gilmore

Considering that the PCV valve is less than 5 bucks, I would say yes, that seems like a pretty reasonable course of action. Might want to get on that.

I don’t know what their “oil consumption test” consists of, but if you’re concerned about it, I’d try a compression leak-down test. That’ll test the integrity of the piston ring-cylinder seal.

Most auto manufacturers, including GM, consider 1 qt/1000 miles as being normal oil consumption. So 2 qts/2000 miles would be normal consumption.

The engine is most likely burning the oil. Only not at a fast enough rate to be noticed out the tailpipe.


A plugged PCV valve may cause oil consumption, and is a cheap, easy fix. Try it first. The ‘Add Oil’ light is a warning the oil level needs to be checked. If you cannot see smoke from the tailpipe, and no noticable leaks, I doubt the problem warrants any expensive diagnostics yet. Just keep an eye on the oil level. If it is due to piston rings happening to line-up, then it may work itself out. If it is a seal leaking, it will grow until it is easy to notice. Then, fix it.

I have a somewhat similar 2001 Suzuki XL7 and the oil consumption began to increase steadily after 90K. It now has 158K and the oil consumption has slowed back down to about 1qt for every 1750mi. I had both the PCV valve and the valve cover gaskets replaced (in separate visits) and they both seemed to help. I had asked my mechanic for a dye leak test, because I could not see where the extra oil might be leaking.
Go for the PCV valve replacement first, and if it doesn’t make a noticeable difference, then try the cheaper dye test just to be sure there isn’t an engine seal on its way out.

I am now in the habit of checking every 1500mi and dropping in a quart if it is low. At some point if it does gets back to 1qt for every 1k, I am wondering about stopping oil changes and simply replacing it as it goes. (driving ~600mi - week)
Perhaps with filter changes at 7-10k?

Replace PCV valve.

Otherwise buy a case of motor oil on sale and check/top it every 3rd fillup. Far cheaper than chasing the problem if no leaks present.

Agree! If the vehicle runs smoothly, has enought power, is easy to start, and does nor smoke, just add oil after changing the PCV valve, as recommneded. An E Type Classic Jaguar would be consuming 1 qt/800 miles when just broken in.

If you drive 15,000 miles a year, that’s only 15 quarts, and you can buy your favorite oil by the case from oil company bulk depots, that’s where truckers get their oil. Or you can wait for a case lot sale at Walmart.

Unless the oil consumption is confined to one cylinder, there is no real problem. Oil consumption at a rate of 1 quart per 750 miles is acceptable by the automobile industry. A new PCV may help and should be raplaced. And as miles add up more frequent oil checks and changes could be in order if you are looking for the biggest bang for your buck and plan to keep the vehicle till the bitter end.

If the PVC valve is plugged and the crankcase pressurized you may have blown a seal somewhere. Replacing the valve may correct the problem or you may still have a leak.

Watch your coolant carefully. If you’re using that also, I’d suspect intake manifold gasket failure.

You have a “feature”: A car that changes its own oil. Some manual intervention is required, but none of it involves climbing under the car. What a great deal. Where do I get one?

No, if it came on all of a sudden, I have to go with head gasket. How’s your water level holding up?

My 1990 Jetta GLI, which I bought new and sold at about 110k miles, used a quart every 1,500 miles starting the day I bought it. I imagine it didn’t end the day I sold it in 2002.