10K oil changes are BAD! ??

I see 2nd gen Prii also burning oil. I own one of them.

I don't have a way of checking the compression ring tension for all those cars, but I would bet if you compare any of them to any thing 1990's or older, the tension is way lower than it used to be.

Engine friction used to be a huge part of engine efficiency loss. Pistons and rings are a still a huge part of that, but are much better than they used to be.

 

Before the Prius, I had a 1981 Mazda GLC (aka, 323), the first year for that generation. Mazda advertising and press hand-outs at the time the model was introduced (Fall of 1980) bragged about design changes they made to reduce fuel consumption. Steps they listed under the "Engine Friction Reduction" heading included "Reduced spring tension on piston rings" and "Reduced thickness of compression rings."

 

I'm not sure the drain-back holes are any different, say bigger. I seem to recall seeing a video, a guy comparing the two pistons, saying he couldn't see an appreciable difference in the drain holes. The pistons are different (at least in part) because the revised rings won't fit the old pistons; they're slightly bigger IIRC. That may be the only reason for revised pistons.

 

What kind of rate? Gen 3's, once they go off the rails, can be doing a quart every thousand miles, or worse. If you're down like a pint or a quart between changes, that's something you can live with.

 

THIS IS ACTUALLY USEFUL INFO. Thank you!!!

 

Let the FLAMES Begin!! Posted this over on CT200h forums, so thought I'd share here. I watched the video in the very first post of this thread. This guy makes me a bit nervous about my science experiment. He claims that the oil scavenging rings can seize with "gunk" while the oil analyses will look fine. That's a possibility I hadn't thought of. Still, on balance, I'd like to hear if anyone with over 250k miles on their car has gone with 20k mile oil changes, or even 15k.

 

Ok, so obviously oil analysis is reassuring. But there really is still about a quart of dirty oil left in the engine on every oil change...which is highlighted by the mechanic in the YouTube video (at the first post of this thread). Nevertheless, shouldn't increased iron be seen with cylinder wear? Maybe then it's too late, though.

Anyway, this is hopefully a good trial run with lots of data for those of you who are curious. I won't be the guy who has oil consumption at 150k and doesn't report it because I did this. I'll definitely tell everyone so we can learn from data. Maybe I'll be still going to 200k with no sig oil consumption. (I didn't add any during the last 24k oil change interval). Useful input and data is appreciated. Flaming is expected, but kinda useless and boring. You really won't bother me with it though, so flame away!

 

Service fill (normal oil & filter change): 4.4 qts
Dry fill (bone dry like after rebuild): 5 qts

Most of the oil burners haven't excessively worn the cylinders (as long as they've kept oil topped up) so you won't see elevated iron. Low tension rings are part of the reason you can have fantastic crosshatching at 300,000 miles and why, in those engines, you can usually replace the piston & rings (or just remove & clean them) and dramatically reduce oil consumption.

I don't think there is anything on a blackstone oil report that'll indicate you're building excessive carbon & varnish.

 

I cahnge mine every 100,000 miles, wether it needs it or not....

 

I can't find any youtube videos with the prius, but there are a couple going over the changes to 2AZ pistons. On that engine there oil drain back holes are the same size & number, but the angle of the holes changed: the original holes were perpendicular to the piston skirt while the revised piston had the holes slope downward toward the crankcase, presumably to allow gravity to help clear the holes as they cooled. The old piston actually had some cut-outs on the oil control ring's lower ringland which presumably would allow more oil to drain. The new design didn't have those cutouts so all draining oil has to go through the small drain holes.


Perhaps this keeps hot oil from stagnating in the small passageways and prevents deposits from forming as quickly. On top of that piston change, they also changed the oil control ring design (but it is the same height).

 

Is this the oil that you mention?
Mobil 1™ ESP X2 0W-20

I think that we are talking about the same thing, but we do not understand each other.
I am all for oil change interval that is correct. But what I am talking about is that if someone is driving the car in a manner that destroys the oil, off course it needs to be replaced eariler. But why would someone that drives only on long distances with very moderate speed change the STILL GOOD oil at 5.000 miles? The oil that is in a much, much better state than the oil of a car that it drives only 3 miles in stop and go traffic every day and this oil will be in much worse condition at 4500 miles than the oil of the second car at 8.000 miles. Why? It is just throwing earth resources through the window.

I would never go over the recommended service interval from the manufacturer. There are engineers there who know what they are doing although sometimes marketing department takes over. For example cca. 15 years ago Opel went for 30.000 miles interval. Loool. They quickly backpadled that.
But it will be interesting to see what will happen to your car.

Anyway if I remember correctly Hoovies Maserati Levante did not have an oil change for 60.000 miles which is insane and it still drove ok. I also remember an Audi TT that did not have an oil change for around the same mileage and it finally died. So, probably on well designed engines the longer oil interval would not be a problem. But anyway, I do not like that thinking. The engine needs to get good maintenance and this way it will provide a good service to the owner.

BMWs have 2 year oil change but they also measure the driving use and they shorten the interval, if I remember correctly. I am sure of that for VW cars. You can have fixed service interval of 1 year or 15.000km or variable service interval of 2 years or 30.000 km. But the car takes into account the use of the car and it usually shortens the service interval .
Although, when I ONCE tested this variable interval for my use it would be 30.000 km. According to cars data my oil would be still good for 36.000 km of oil change . I replaced the oil at 28.500 km and it was black. After that I went back to fixed service interval and when replacing the oil, you could still see a golden reflection at the top of the black oil.

Anyway, I would immediatelly sacrifice the difference in the fuel consumption due to normal piston rings to the longevity of the engine. But that was obviously the wrong decision on the Toyota side.

 

i have read gm did that on the volt, haven't seen anything from toyota, i don't know how accurate/reliable it is.

 

Sadly all car manufacturers say that. In my Toyotas owners manual there is a statement that burning 1l of oil per 1000km is normal. Huh.

 

Mine burns so much oil I technically do an oil change every 2500 miles lolz

I wouldn’t dream of going 10k on an oil change even if I could. Especially the way I drive.

 

Read your Owner's Manuals. Until fairly recently, every car I ever owned called out oil consumption on even a new engine to not be a warranty problem unless it exceeded 1 quart per 600 miles. I think the Prius tightened this to 1 quart per 1000 miles, and the household's Subaru tightened it slightly more to 1 quart per 1200 miles after break-in, i.e. excluding the first few thousand miles.

Perhaps we should also distinguish between what consumers consider 'normal', and what car makers consider 'bad enough to trigger warranty coverage'. There seems to be a wide gap. And do note that if the oil level runs too low because the driver/owner never checked it over thousands of miles, the warranty is voided.

 

I'm not sure it totally counts as an oil change though, because I'm guessing what gets around the rings best is the cleanest stuff, and what stays behind is the gunk.

 

Thanks for posting your preventative maintenance procedures!
I too would like to here from high mileage owners.

There are specific Ring Soak products that might be stronger than Seafoam.
I have a courier friend that has a few high mileage Prii.
He's has had good results with performing a Ring Soak. I don't remember the exact product his shop uses, but the procedure is to have the pistons mid stroke and let the Ring Soak sit for days, until it's all in the pan and the oil control rings and drain holes are hopefully clean or at least the crud is loosened up. Obviously they do an oil change before starting the engine.

My booga-boo is the dang head gasket going bad at high miles. I had one start to go out on my last Gen3. I bailed on the car.
Now I'm about to get another Gen3 with 122k miles on it.
I'd like to do whatever is needed to make it last as long as possible.

 

I was slightly joking, but I imagine you're right. Oil burning and having to top it off all the time can't be good. I forgot the name of the stuff, but I did do that chemical engine cleaning treatment.