Only 5 quarts drain in oil change?

Just curious if anyone else has seen this. 2012 4 cyl tacoma 4x4. I do my own oils changes. I drain the oil with the oil cap off, empty the old oil filter into my drain pan, etc. When I pour my waste oil back into the containers, I barely get rid of 5 quarts but when I replace the oil, I put in 6 quarts. It puts the dipstick in the correct range. My truck doesn’t appear to burn oil, I can’t see any smoke or anything while starting it or driving it. The truck has 138K. I’ve done the last 4-5 oil changes myself and each time, I only have to dispose of roughly 4-5 quarts of oil even though I put 6 whole quarts in when I do the oil change. I drive super easy on the truck, in fact I just had the original front brakes done at 137K and there was still a little life left in ththe pads. I do wait 10K to do the oil. The truck says to do it at 5k and I do it around 9-10k and use good 0w20 synthetic oil and a high mileage oil filter. If I can’t see it burning any oil, I’m wondering where the 1-1.5 quart is going between oil changes. Thanks!

 

Burn off, and oil that still stuck in the engine’s nooks and crannies.

 

The filter will hold some

 

Do you keep an eye on the dip stick? Or do you just toss 6 quarts in and go? If the latter you may be fairly overfilled. These engines take a long time to fully drain. On my last I popped the drain plug off, rotated the tires, and when I came back there was still an appreciable drip.

 

Keep doing what you are doing.

Yes, it seems weird, but there's not a problem.

The 'lost oil' is clinging to engine internals (and within the old filter.) All the oil will never drain out, nor would you want it to, because then you'd have dry parts every startup.

 

Do you ever check the level between those 10k changes?

 

Saturated oil filter media can hold 1/3 to 1/2 quart of oil.

 

The math says you’re burning about 1/2 quart or more between changes. Oil clinging to the engine internals doesn’t count as it is relatively static.

 

Some oil never makes it back to the drain pan. Some is burned even if you think you see no smoke.

 

Check your oil in the morning before you start your truck, snap a picture of it , and do this every month or 1000 miles. If you see a even decline of the oil level, its probably the nature of the ageing beast. If you go several months and then start to see a steady decline in the oil level, you may be asking too much of your oil. Reduce the maintenance interval , in the latter case.