I've been changing oil for about 65 years for myself, GF's, parents, kids, grandkids and friends.
I pour the drained oil into old milk or water jugs for recycling. (It is amazing how long oil recycling has been available).
I can't remember the first time I looked at what I had drained and wondered how it always happened that I had replaced it with substantially more.
Yesterday it was 3 5/8 quarts into my Pathfinder, as called for and perfect on the dipstick before and after.
Today I measured the oil I drained at 3 quarts.
This difference may be a less than I've noted 10+ times with 5+ vehicles.

Anybody noticed this phenomenon?
Anybody know why?
I have some ideas, but none I like.

I have some ideas, also.

You won't like them either, too.

If you're not seeing something super obvious like drips or wet with oil or a puddle, consider this. You're not emptying the crankcase. There's oil in there even if you let it drain a long time. Also, you're probably changing the filter too, how much oil is in the dirty filter? And a certain amount of oil is going out the tailpipe. If your rings are bad then more is getting into the cylinder, but even a brand new engine has a positive crankcase ventilation system and some of that atomized oil is plumbed into the intake, and burned.

Some thoughts....

Always change filter with contents joining drained oil in pan. (Except the 1/2 ounce or so that Nissan designed to get away to drip on floor. Always parked inside on same place on concrete.)
100,000 miles on engine, always full on dipstick, no add necessary between changes.
Baseline is the same: drain 'til no drip, start with 3 5/8 qts.
3000 to 4000 miles later the 1/2 quart or more is gone.

But keep in mind, I get the same mystery with other vehicles.

Grav: Try me with the bad possibilities.

I too have always done my own oil changes. From twice a year, using regular oil, in my Datsun B210 V4 ... to now annually, using full synthetic (with Z-Max additive during wintertime) in my Hyundai Sonata V6.

As BigV said, all vehicles burn some oil. The more mileage there is on the vehicle, the more wear there is on the parts. As the parts wear down, the spaces between them become larger. More oil goes into those spaces; so, more oil is burned off. A half quart or so, over 3,000-4,000 miles, on a vehicle with 100,000 miles on it is not unheard of.

Your oil change interval suggests you're using regular oil rather than synthetic. Synthetics are expensive; but, more heat stable and you may see less burn-off. Synthetics can go for longer intervals between changes too, The engine could even last longer; however, it can't be a very old model with seals that aren't compatible with synthetics and the vehicle has to have been well maintained so there isn't already a potential leak. Synthetics will clean out sludge that may be plugging an existing leak.

A compromise may be to run a High Mileage Synthetic Blend in the engine at the next oil change. Those have additives to help plump up seals like when they were newer so they won't leak. It might cut down on the burn-off loss, do just a little cleaning, and slow down further engine wear. That' s what I would do in this situation. If there's no appreciable difference, you can always go back to just regular oil.

Moving many...

No doubt there are things I still need to learn after 60+ years of wrenching, but nothing mentioned here so far is one of them.

Seems likely that is Australia.

Chinese double-parked hauler. Might be 21 or?:
https://en.wikipedia.org/wiki/File:C...ransporter.jpg

This isn't an automotive website. Use the right tool for the job.

Looks like 21 to me, four door sedans too. Must be robust tires on that rig. :eek:
Sure it is, we do it all. :haha:

Jack of all trades... etc.

Absolutely, amateurs, anecdotal experiences, no expert instruction on any subject, no liability, no legal grounds to sue.

I reached for it but got you.

And no help either to hear DJ tell it...

OTOH, the grumpy old men are hanging together instead of bickering with each other. That's nice. ;)