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Losing oil

2000 Silveratdo 2500 4wd vortec

I’m now requiring ~1 qt of oil about 1k miles before each 5k oil change. There is no oil under the vehicle when left standing. Based upon this skinny info is there anything that I can or should do to lengthen the time until $ engine work is necessary?

Why do you think engine work is necessary? 1 qt of oil per 1,000 miles is often considered “normal” oil consumption. As long as you maintain the correct oil level you can continue driving. You didn’t tell us how many miles are on the truck, which might make a difference.

You could try having the PCV valve cleaned. If it’s not working correctly it could increase oil consumption.

If I’m reading this correctly you need to add 1 qt of oil after 4,000 miles? That is perfectly fine. Some oils burn off quicker so your next oil change you could try a different brand of oil. Adding a quart of oil every 4000 is actually pretty good for a 2000 truck.

I don’t think major engine work is looming. Changing your PCV valve is a good idea if you can’t remember the last time it was changed. A stuck valve can suck extra oil as part of the crankcase ventilation system. Otherwise, I’d change the brand of oil, consider changing the oil every 3K to 4K miles, or switch to a synthetic blend of oil.

For such a large engine 1qt per 4000 miles is excellent.
Many engines half its size do worse.

I think you are doing exactly what you should be doing, checking your oil level periodically. It is normal for an engine to use some oil as it ages. Using 1 qt/4k miles is pretty good for an engine with a 150k miles on it.

Overtime, you will see the rate of consumption rise. By the time this has about 300k, you will probably be going through a quart of oil every 500-1k miles. Don’t panic, the cost of trying to “fix” it could and probably would be far more than the cost of a quart of oil every now and then.

Checking the PCV valve would not be a bad idea, but I doubt it is the problem. You might also check around the valve covers for signs of oil. If you are handy and you see some evidence of seepage, you might want to replace the gaskets. Don’t expect too much from that though unless you see evidence of a lot of oil seepage. Most of your oil loss is due to normal ring wear.

If you are using 5w30 oil, and you don’t live in the far north, you could switch to 10w30. I would not go any heavier than that.

That’s reassuring. The reason for my concern is simple. I know that the truck did not require added oil between oil changes when it was newer so I figured having to do so as described was an indicator of something not good.

I have the oil changed at a Grease Monkey that is very, very thorough and not $ pushy. I’m fairly certain that the PCV valve is on their checklist and they have not mentioned it as problematic. What’s the probability that the valve could be causing a problem and not turn up on their diagnostic?

I’m not sure what their “diagnostic” would be. Bu the only real way to tell about the PCV valve is to literally check it. The next time you go in just ask them to have a look. Or better yet locate it (I don’t know exactly where it is on this truck), pull it out, look at its conditions & give it a shake. It should rattle. Or just stick a new one on - they’re only a few bucks. It does also have a passage of some kind that feeds it - make sure that isn’t gummed up.

If you’re using a quart of oil every 4,000 miles you do not have a problem. There is no diagnostic to be done. Nothing is broket to fix.

It’s perfectly common and natural for an engine that doesn;t use any oil whatsoever when new to begin using a small amount as it becomes higher mileage. And it is not at all an unhealthy sign.