Not Much Oil In Engine, But It's Up To The "Full" Mark!

Maintenance Question - Oil Changes

2009 Chevrolet Impala LT 4-Door (Wife’s Commuter Vehicle)
3.5L V-6 w/Automatic Transmission
20,000 Miles

Motor Oil Used: (4 quarts) Mobil-1 Extended Performance 5w30
I change my own oil and while the car is under warranty (100,000 miles / 5 years)
I will continue to use AC PF-61e oil filters as specified.

I just changed the oil and filter again (wife drives over 5,000 miles < 2 Months) and although it’s easy to do on this engine, the thing that concerns me is that the engine oil capacity (w/filter change) is only 4 quarts. 4 quarts fills it to top of range marked on dipstick, but it is disconcerting when I drain the oil and get slightly less than a gallon out of it. It just doesn’t look like much oil. I’m used to seeing 4.5 to 5.5 quarts as in our other cars.

I check the oil every week-end. The car uses virtually no oil between changes at 5,000 mile intervals and I’ve not had to add any.
The last 3 changes Oil Life Remaining (on OLM) at 5,000 mile changes:
10,000 miles . . . 38%
15,000 miles . . . 40%
20,000 miles . . . 34%

The 4 quarts bothers me (except the savings on Mobil-1). It’s just such a small amount. Do you think I should try putting in a few more ounces ? How many more ? Should I throw in 8 ounces and see where it lands on the dipstick or just leave it alone ?


I don’t see a reason to be concerned. You’re filling it with 4 quarts and draining it of slightly less than 4 quarts.

What’s wrong with that?

I wouldn’t worry about it and would only fill it to capacity, nothing more. Keep doing exactly what you are doing and you will probably get 300k trouble-free miles out of this engine (yes, even though it’s not a Honda or Toyota). GM, in my opinion, usually does a pretty decent job of engineering engines, and the fairly low oil capacity would not concern me. The last Chevy 350 I had only took 4.5 quarts to fill even with the rather large oil filter.

CSA, I think that if the specs on an oil change give 4 qts & you do the change & 4 qts leaves it at the full mark, then I think you now have a case of paranoid hyper-vigilance. I get it. A car that you must have bought new or nearly new. Still has low miles on it. Maintain it impeccably to get the most out of it & all that. I’m guilty of some paranoia even on my old beaters. But its paranoia nonetheless. Stick with the 4 qts & sleep well at night.

When something goes messy on that car it will be the transmission. Do some early research on the common issues. They’re apparently great transmissions - when they work. They just have some real quirks that can be problematic to get sorted out.

I think the missing oil is in the filter!

“I think you now have a case of paranoid hyper-vigilance. I get it.”

That’s me !

Some people sweat over one or two cars. I keep so many cars on the road at once that I am always changing oil or doing some type of maintenance. Most of you know what I’m talking about. I have to stay on top of it.

Thanks everybody for all the reassuring comments so far. Keep them coming if you got some.


I have a friend that was a cross country trucker, also very vigilant about oil changes. I was at his house one day and he had taken his daughters car, a late 90’s buick something or other in for an oil change. He proceeded to add another quart of oil, saying it is something he always does. I was thinking what what what? but he had been doing the same practice from the 70’s, and figured I might as well just keep my mouth shut on this one. I am still wondering about that one, but look on the bright side, it could be worse!

4 quart capacity is nothing to worry about. Most of the time you’ll get slightly less oil when draining the oil, because your filter will probably have 8-16 oz, plus even thought it might not be enough to show up on the dipstick you may have used a few ounces. That’s the capacity of my '88 Ford Escort with a 1.9L engine it’s now got 517K miles and is still going. As long as you don’t allow the oil to get below a quart low you’re fine. I try to keep an eye on my oil level and if it gets to 1/2 quart low on oil I top it off unless it’s nearly due an oil change then I just let it go until the oil change is due. It’s better to run an engine slightly low on oil than to have it overfilled. Overfilling can damage seals and gaskets in the engine.

My wife has an '87 Chevy Celebrity with a 2.5L engine and the oil capacity of it is only 3 quarts. It’s got almost 180K miles on it.

Hmmm, Is this a math test or something? There are four quarts in a gallon, correct? You put in 4 quarts, and get almost 4 quarts back out again plus whatever would be still contained in the filter. 4 in 4 out? I’m not seeing a problem yet. Maybe next oil change put a gallon in instead and see what you get out. I don’t think you will get 5 quarts out of it if you only put four in. I may be wrong though.

4 qts is a gallon. You drain slightly less than a gallon and refill with 4 qts; I fail to see a problem? There is oil that comes out with the filter and the new filter soaks up some oil. Refill with 4 qts or until you get a full reading on the dipstick.