Another oil burning thread

In theory that would only happen if the oil pressure was insufficient at lower RPMs. I am going to risk an opinion that Prius engines trending excess oil consumption is due to improper maintenance and/or not checking the oil level regularly by the owners. I have over 70K miles and no measurable oil use, but I change mine at 5,000 miles and check level religiously.

 

It seems that many vehicles with small Toyota engines (1.5L and 1.8L) tend to consume oil after more than 150,000 miles of use regardless of the vehicle that they are installed in (Prius, Yaris, Corolla, etc.).

The two Honda Civics (with 1.5L engines) that I have owned did not use very much oil even after 200K miles.

The main difference I've noticed comparing the Honda and Toyota engines is that the Toyota engines have had oil varnish deposits in the cylinder head while the Honda engines were free of these deposits. Oil varnish is produced when the oil temperature exceeds about 180°C. So, it appears that the Toyota engines ran hotter than the Honda engines for some reason. Major brand synthetic oil was used in all of these engines (Mobil 1 mainly).

If this is what is actually occurring, then it's likely that the Toyota engines start consuming oil when the valve train experiences wear due to less than optimal lubrication in the cylinder head. The engine oil has three functions: maintaining a film between the stationary and moving parts, trapping and removing wear debris, and reducing friction.

Consequently, when enough wear has occurred, a noticeable increase in oil consumption occurs.

 

Oil consumption doesnt worry me as much as decreased mpg's and ICE performance.

I once owned a GM truck that consumed 1 quart every 1000 miles that started at 20,000 miles. GM said it was normal, whatever, I drove the truck and sold it with 260,000 miles on it. It religiously got the same mpg's (11-14, lol) and never showed a decrease in performance.

 

Concur.

I've talked with a lot of Prius drivers over the last three years who never check their oil. They just take it to the dealer or a Jiffy-Lube when it needs service.
30 years ago, that would have meant that the "replace owner" light would be illuminated before 50,000 miles.
Now you're almost guaranteed to see 100,000 miles even with a half-hearted attempt at maintenance.

 

Another aspect of this discussion: What would be the difference in wear factor, rev for rev, in using the engine in B mode when it is just compressing air, compared to normal when it is burning fuel? I go down long hills, and using B mode can get the engine spinning up to 4000 rpm for a while, although the engine temperature is lower than when going up the same hill. If I don't use B, then I am using more friction braking.

I now wonder if, down the road, I will be better off replacing brake pads sooner, than risking increased wear of the engine.

And I do check the dipstick often!

 

I don't think that using the engine in B mode often is a bright thing to do, but I understand that sometimes people live in areas where its use is necessitated by hills, etc.

It can't be any worse off for your motor than a regular ICE using compression braking, and in fact it's probably much better since you're not dealing with the stresses of combustion. As noted above...temps (for those with a gauge) are usually lower. I generally eschew compression braking myself (except when in the mountains) because brakes are a helluva lot easier and cheaper to replace than engines.
I do it, but not often enough to have much of an impact on a motor over a 300,000 mile life cycle.

Even with the Atkinson cycle, I would expect the 1.5l motor in a Prius to OUTLAST a similar motor in a Corolla since some measurable period of the motor's life cycle is spent with the engine shut off while the car is in operation.

I'm pretty sure it's a combination of sloth and an extended oil service period.
The change interval is different in Canada, and in other countries after all.
I think that the folks in the head-shed calcu-guessed that the typical American driver keeps the car for X number of miles before the car is parted out and developed a motor with a life-cycle of X+y% and the 10K change interval is part of that.
The sloth is a contributor because the oil may LAST 10K, but that's only true if you maintain volume, and the only way to accurately measure that is to measure it.
Waiting for blue smoke or an illuminated oil light works too.

....just not as well.

 

Most people who do at lot of miles also tend to do a lot of highway miles, which means that the engine is running (or least turning) nearly all the time.

As for people who drive slower routes where the engine genuinely is off for a significant percentage of the time, I suspect that the delay in oil reaching optimal temperature may be more of a detriment to the engine than is the reduced number of revolutions a benefit.

 

My 2007 with about 272k was burning 1.5 to 2 quarts of oil for every tank of gas. Now at 285k miles it is burning 1 quart every 3,000 miles. A BIG IMPROVEMENT. I had to replace the catalytic converter in the car. Hopefully the current oil burn rate will not kill the CAT. If anyone knows I would love to hear. Also the oil now stays clean whereas before it would get dirty very fast and by putting a camera down the spark plug holes I noticed the cross hatch groves in the cylinder walls. so i think I can get some more miles out of this engine. But in California Catalytic converters are VERY EXPENSIVE. So running the engine to the bitter end does not really pay!

What did I do? Put 4oz of Sea Foam down each spark plug hole and let it peculate down through the two compression rings and the oil ring and the oil passages to the bottom of the piston. Probably overnight works 18 hours with just a rag over the spark plug holes left the pistons dry in another Prius. I have pictures and more detail at Burning oil problems due to dirty piston rings (oil & compression) and prevent catalytic converter problems and keep the oil cleaner for a longer engine life.