oil consumption vs length of oil change interval

EEK! MATH!

[runs away and hides]

 

Dipstick method works just fine. Sorry, no sale.

 

Touché! Nice one. Still not going to do it.

 

You guys need to get a life !! if it use 1/2 qt in 5 k miles it will use 1qt in 10,000 miles its synthetic oil it won't break down in 10k miles. Just add oil at the add mark and stop at the full mark. Its not rocket science.

 

You must be a woman...men NEED to make things more complicated when it comes to auto maintenance.

 

Not a woman just old enough to know what really matters in life

 

People, if you're weighing the oil filter to figure out how much was lost over thousands of miles between changes, you don't have a problem with oil consumption!!!

When you start adding a quart or more between changes, then you can start talking about how much oil is being consumed. Otherwise my brain just throws a divide by zero exception. (did I just give away what I do for a living?)

 

20 ounces of mobil 1 0-20 every thousand miles and the Prius was bought new all oil changes at 10,000 miles done at the dealership so she is starting to use some , car is driven 50 miles 5 days a week .

 

Just joined because of this oil consumption issue! Bought a 2010 Prius used 3 years ago with 55k miles, OCI of 10k per dealership's recommendation (0W-20). After my first "no oil!" crisis around 100k (I know, I should have been checking levels on my own...), I happen to be going to a new mechanic, who put me on an OCI of 6k. I've been consuming at about a rate of 1 qt per 2k miles, but no significant leakage from the engine, no white smoke out the tailpipe, no unusual oil residue on the spark plugs.

 

Up until the time I traded in my 2010 Prius 3, it was burning 1 quart every 1,530 miles. I had bought it used from a toyota dealer with 33k miles on it. I believe it was a rental car, which may explain some things. We had the oil changed every 10k at the dealership. Started using oil around 90K miles and it had 160k miles when we traded it in. Like other people have said, the car never had an oil leak or blue exhaust.

 

Agree. Reasons:
Viscosity breakdown of the oil base or the viscosity thickening chains that increase the viscosity from 0 to 20. Either would allow more possible metal to metal contact under certain operating conditions .
The additives package including the anti-wear additives is very important to modern oil formulations , and those additives are consumed over time and miles of use , so over 10,000 would risk increased wear.
The extreme frequency of start-stop cycles in normal city driving of a Prius would exacerbate these effects on harming the ICE.

 

Thanks Robert. I'm amazed that you could sift through my verbiage, understand it.

 

I'm going to disagree for the sake of debate

If a manufacturer is recommending 10k intervals, you can assume there's some padding in there before serious consequences occur. Years ago a friend had an early 90s Tercel that had an oil change every 20k miles if it was lucky. That car lasted at least 100k miles. At most, delaying an oil change will cause a moderate increase in wear.

So what are the serious consequences of not changing your oil? One word: "Sludge". When oil changes to sludge, it blocks screens and oil passages and now your engine has areas that receive no lubrication and the result is rather sudden death. To make things even more complicated, sludge can be caused by things such as a small leak that allows coolant to mix with the engine oil. Thus one engine may be fine on 10k oil changes, and another "identical" engine will sludge up within 3k miles.

If the oil is changed before sludging occurs, there won't be any damage to the engine. In fact, there's this thread that suggests the possibility that wear may actually *increase* following an oil change: Increase in wear following oil change... | Passenger Car Motor Oil (PCMO) - Gasoline Cars/Pickups/Vans/SUVs | Bob Is The Oil Guy

 

What this thread needs is some hard data concerning extended oil change interval in a Prius... & I happen to have that

My last 4 oil changes have been at 9.7K, 12K, 14K & 15.2K - currently I'm at >16K & still going.

Each of these oil changes had a sample sent off to Blackstone Labs.
Each time the report came back perfect & they suggested going an extra 2K over the previous oil change interval.
Here is a snippet from the last report:

"Wear couldn't look better -- it literally couldn't -- and not only is there no measurable fuel, there's no coolant, water, or abrasive dirt contamination either. The 3.4 TBN shows plenty of active additive remaining for a longer run, and with samples this nice, 17,000 - 18,000 miles should be a piece of cake next. Don't change a thing... your maintenance routine is perfect."

That is why I am at >16K & still going...

2010 Prius - Purchased used from original dealer as a trade it at 100K
Mobile1 0W-20 Extended Performance 15K - the same oil has been used throughout.
Filters have been OEM purchased locally from dealer.
Prius had 128K when I started this test. Currently it has >193K
Prius has _constantly_ used oil at a rate of 1qt/5K

 

ps: I _always_ add oil before the engine gets 1/2 qt. low.
Typically I add 8-12oz. whenever it gets a little low.

 

That's interesting.
I used to consider the "stuck ring" as an alternative to "worn cylinder sleeve" or "worn oil scrapper ring" for explaining loss of compression and increased oil consumption on my motorcycles. If I found a lot of carbon in the ring groove, I would scrape it out as best I could using an old broken piece of ring of the correct width, but then usually install a new set of rings, hone the cylinder walls, and pray everthing would re-seat after reinstallation. But that was long ago and I have not heard of people doing this to Prius ICEs.

Related question: on some vehicles we could remove cross members under the oil pan, remove the oil pan, and then unbolt each connecting rod cap nuts and carefully pull the rod and piston down out of the engine without removing the engine from the car. Does anybody know if that trick will, or will not, work on the Gen 3 Prius because if it does, you can replace rings and decarbonize the piston crowns without using an engine hoist to remove the ICE.

 

This paragraph from that report cites possible mechanisms:

"Testing with partially stressed oil, which contained some wear debris, produced less wear than testing with clean oil. This finding was unexpected and initially confusing (further inquiry suggested that the result was not so surprising, as many oil chemistries require time and temperature to enhance their effectiveness). Although based on limited data, the finding could be significant, and verification should be pursued. If the finding is verified, the mechanisms should be determined, and ramifications with respect to oil change intervals, filter involvement, and additive packages should be considered. A similar finding for diesel engines could have even greater significance, since the topics of extended oil drain and, in some cases heavy exhaust gas recirculation are of major interest. Although the conditioning run altered the oil, it did not stress or render it unusable (as noted, there is indication that it was tribologically improved). As such, the impact of testing with significantly stressed oil was not measured and remains a future objective."

This would suggest a negative impact of changing oil every 5,000 miles, which quite a number of PC folks seem to do. Hmmm.

My data was from the Consumer Union survey of long-term car owners that was done in the 1980s or 1990s (?) , but clearly their results indicated better longevity for cars with oil change intervals of 3,000 miles. Based on that I concluded more frequent changes were better. Now I have to re-evaluate. I am very reluctant to go above the 10,000 limit specified by TMC, however.

 

I'm NOT joining that group/
5k or once a year it is ////