Burning more oil on highway than around town, why?

What is your average engine RPM in highway driving, compared to around town?

I've never had a car that didn't burn oil faster at higher RPM.

I've never thought the PCV circuit had to be the only path or most important path. The cylinder walls are a path. Piston rings can only be so close to perfect.

 

If you know you have issues; you should be checking at every fill-up. That's a good rule that seems to have gotten lost by the computer generation.
I was helping my friends daughter move to the east coast for her graduate program. The first fill-up; I didn't say anything. The second fill-up I mentioned it; still nothing. On the third fill-up; I insisted. It was 1.5 quarts low, not touching the dip stick. We were only about 1K miles into the trip; so I had to ask - "Is this how you were planning on getting another car?". We had a good laugh over that; because she knows better. Blasting down the highway averaging 80+ mph will do that to an old Lexus engine with 200K+ miles on the clock. It had a 5-6 quart sump.

 

It's interesting how we call it burning oil when there's no leaks on the outside because the loss of oil isn't as straighforward as it just burning, but how it circulates in the engine. Would be great if someone like you or someone else who knows alot could help explain the finer points of this subject.

 

I'm not sure much effort is needed to brainstorm modern-tech, hybrid-specific explanations for a phenomenon that's been around since ancient cars: sustained operation at higher RPM burns more oil.

The speeds one considers to be "highway cruising" make a difference. My Prius doesn't use a lot of oil in my normal highway driving, at or around the PSL. By contrast, one time I got a late start leaving for a friend's funeral in Boston and made that Indiana-to-Boston cruise at, shall we say, a sustained speed that made up the time, and there was noticeable oil gone after that. No surprise there.

The lowest ring on the piston is called the oil control ring. It usually has a more complicated construction than the two upper, "compression" rings. It's more like two skinny rings and a kind of waffle spacer. When the piston moves upward, the cylinder below it is crankcase, and gets oil splashed up on those cylinder walls (or even sprayed by dedicated nozzles, in some engines). When the piston moves downward, the cylinder above it is combustion chamber, and whatever oil is left on those walls gets burned. The oil control ring should have squeegee'd most of the oil back down the walls into the crankcase, leaving only a small amount to end up burning. Still, at 3000 RPM the piston is going up and down 50 times every second, in every cylinder.

The PCV path is, of course, also a path.

 

The engine runs less, and occasionally shuts off completely, around town, versus fulltime running, at higher rpm on the freeway. Sheesh, next question.

 

This is all a moot point; if you check your fluid levels at every fill-up. It only takes a minute while the tank is filling. I don't understand the resistance and how someone can blame the OEM for blowing up an engine because it wasn't properly maintained.

It seems kinda obvious to me; if the engine is running - your burning gas and should check all your fluid levels every fill-up. Assuming you have no fluid leaks hitting the ground. It's better than guessing and develops good routines that will prevent high cost repairs.
An ounce of prevention is worth a pound of cure....

Just my 2-cents......

 

5 minutes works for me. Pull/wipe the dipstick, check tire pressures, then back to the dipstick check.

That said, an immediate check has also been working "fairly" good. The face of the dipstick towards front of car tends to be clearer in my experience.

 

I was taught by my father, a trade-certified (A-grade) motor mechanic, to always wipe the dipstick. I have always done that and would never do otherwise.

I’ve found with the Prius that one side of the dipstick always looks consistently better than the other, and if I recall correctly, it’s the side facing the front of the car. Also, you’ll notice there is a curve to the dipstick; I always replace it so that the curve follows the direction of the bend in the dipstick tube.

 

I've pretty much always just stopped the car, turned it off, pulled the fuel door and hood releases, gotten out, fiddled with the pump and the credit card and the hose and nozzle, started the fill, walked to the hood, opened it, pulled the dipstick once, wiped it, dipped it and pulled it again, and read it. It hasn't ever seemed especially hard to read. (Well, it is hard right after an oil change, because the new oil is so clear. It gets easier and easier until the next change.) I do find one side easier to read than the other. I still always look at both.

 

I've got a rag stuffed in the engine compartment for that purpose. Drive-thru napkins in the door pockets; if the oil is new. Just look for the wet spot with the napkin to get an idea of the oil level. It doesn't have to be perfect - you just need to make sure there's still enough oil in there.
Listening for a rod knock or watching the oil lamp illuminate is the other option. Unfortunately, either one of those is going to be a costly repair.