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Old 12-03-2019, 02:54 PM   #16
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Re: Why do engines "use oil"?


@Colbyt and @Brainbucket sum it up pretty well. All I would add is that burning is typically much more of an effect on oil consumption than loss by leakage. Virtually every car on the road is leaking some amount of oil somewhere. It doesn't always make it onto the ground in your driveway.
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Old 12-03-2019, 02:54 PM   #17
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Re: Why do engines "use oil"?


Quote:
Originally Posted by Brainbucket View Post
The pcv valve was sucking the oil from the valve cover. I had the slow the air flow down. I stuck piece of a crank case breather element from a 83 GMC and put it in front of the pcv valve.
A lot of DIYers put a catch can in. GM had to redesign the valve covers on a few engines with a deflector because of that.
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Old 12-03-2019, 03:24 PM   #18
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Re: Why do engines "use oil"?


Why do engines use oil?

Because no one bothered to put Martini's, Manhattan's or Old Fashion's in them.

Although a few of them did run on moonshine...

Ba dump, bump...
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Old 12-03-2019, 06:29 PM   #19
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Re: Why do engines "use oil"?


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Originally Posted by DoomsDave View Post
The engines in my more recent cars (well, the newest is a 2001) seem to "use oil". What, exactly does that mean? Is it burning oil at a low enough rate that you can't see it? Or maybe leaking somewhere in little bits?

Any thoughts?
hot oil evaporates over time which is why we have the NOACK test/ASTM D5800.

oil is left on parts (i.e. cylinder walls) on purpose and is slowly consumed (oil control/scraper ring does not remove ALL oil, nor should it).

blowby/PCV moves atomized oil out of the crank case (the separators aren't perfect) into the intake.

turbos love to consume oil due to the styles of shaft "seals" used (i view it more like the oil is given the opportunity to return to the oil pan, most of it choses to do so).

lastly, worn parts leak oil where they shouldn't (to the outside of the engine, valve stem seals leak into the intake/exhaust systems, etc).
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Old 12-03-2019, 06:36 PM   #20
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Re: Why do engines "use oil"?


Uses oil because you put Motor oil in it. Find a bottle of oil that reads Engine oil and try that.
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Old 12-03-2019, 06:43 PM   #21
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Re: Why do engines "use oil"?


My car, a 2000 BMW 5 series, uses no oil between 5k mile oil changes. The following year of production, they made some modifications to the engine, which included changes to the piston rings, and those cars have earned a reputation as oil burners, with some burning a quart or more every couple thousand miles.
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Old 12-03-2019, 06:47 PM   #22
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Re: Why do engines "use oil"?


Quote:
Originally Posted by 3onthetree View Post
A lot of DIYers put a catch can in. GM had to redesign the valve covers on a few engines with a deflector because of that.
I had a lot of blow by so I put one of the catch cans on our Sentra, it does work, at least it did on ours til the blame engine went south. You can check to see how much blow by you have by cranking the engine and take the oil fill cap off. Be ready to put the cap back on quickly, because if it has a lot of blow by you are going to spray oil everywhere.
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Old 12-03-2019, 06:50 PM   #23
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Re: Why do engines "use oil"?


Here are photos that will help to understand what happens when the oil problems mentioned by @Brainbucket occur. The piston rings are supposed to scrape extra oil off the cylinder walls during the down stroke. The oil is then supposed to go through holes on the side of the piston and then drop back down into the oil pan. If the rings or holes are clogged, the oil is instead left on the cylinder walls and is burned to escape as combustion products with the exhaust (including soot). Some of the carbonizes on the piston, exacerbating the inability for the oil to be returned to the oil pan.
First photo shows fouled piston rings and clogged holes. Second is after it was cleaned, holes drilled larger in diameter and extra hole added.
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Why do engines "use oil"?-20170413_182830.jpg   Why do engines "use oil"?-20170413_002019.jpg  
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Old 12-03-2019, 08:04 PM   #24
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Re: Why do engines "use oil"?


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Originally Posted by ktownskier View Post
Why do engines use oil?

Because no one bothered to put Martini's, Manhattan's or Old Fashion's in them.

Although a few of them did run on moonshine...

Ba dump, bump...
Which is why I don't use oil, neither . . . .
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Old 12-04-2019, 09:17 AM   #25
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Re: Why do engines "use oil"?


Quote:
Originally Posted by sestivers View Post
@Colbyt and @Brainbucket sum it up pretty well. All I would add is that burning is typically much more of an effect on oil consumption than loss by leakage. Virtually every car on the road is leaking some amount of oil somewhere. It doesn't always make it onto the ground in your driveway.
This. Cars leak oil. Look at any place on the road where there's a bump or dip. You'll see the pavement around it with an oil slick around it from the thousands of tiny drops of oil that get bumped off cars when they're jostled over the bump.
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Old 12-04-2019, 09:42 AM   #26
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Re: Why do engines "use oil"?


I have no doubt BB covered this, we are normally on the same tune.
Oil consumption is due to new and improved pistons design. I.E., lighter, shorter pistons with very short "head".
In pursuit of faster revving, better mpg/power engines, designers try to eliminate any weight and mass possible. Hence, they reduce weight and size of moving parts, piston being one of them.
Shortened piston "head" and use of light alloys leads to them overheating not just at the leading surface but, also, across the entire upper section. That, in its turn, leads to quick oil burn out, caking, in very now small oil channels. That, in its turn, leads to caked piston rings, losing its function as seal and oil into crankcase drip prevention.
Next reason is same in origin. Very short piston contact surface to cylinder results in piston ever so slightly oscillating in the cylinder bore, as it does not have enough contact surface to mate snug with it and wobbles while going up and down.
Yet another reason is drive towards very high compression, what forces hot gasses into crankcase past short piston head.
Last, but not least, is lack of proper engine break in. Engines are baby-d, thus, rings are not properly set into the cylinder bore and start leaking soon enough.

Cheers. Buy old heavy engines with huge heavy pistons. No race horses but ain't got that problem. This is why diesels are slanted to death. too reliable as, partially, if you look at pistons - they are about twice as large and everything is beefed up as possible. No good. They need to SELL new cars, not make them run forever.
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Old 12-05-2019, 08:01 PM   #27
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Re: Why do engines "use oil"?


Quote:
Originally Posted by Windows on Wash View Post
Engines use oil because people run cheap dino oil instead of synthetics...

@ron45



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Old 12-06-2019, 10:39 AM   #28
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Re: Why do engines "use oil"?


I've had the vehicles checked and the mechanic says they're not burning oil. I think @ukrkoz 's point is on target; it's the newer engines that have had that issue. The old boats I used to have don't do that.
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Old 12-06-2019, 09:21 PM   #29
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Re: Why do engines "use oil"?


Yep. My 98 MGM (188 000 miles) eats miles and drinks NO oil. Not even sure why I do 5000 miles oil changes. But my 2019 RAM with 6000 miles on it already has soot in tailpipe.
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Old 01-06-2020, 11:37 PM   #30
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Re: Why do engines "use oil"?


DoomDave there are a lot of posts in this thread but only one was
100% correct! (facts and nothing but the facts)

His post was not the long drawn out explanation filled with cliches or old wise man tales, his post was neat ,clean and to the point.

So IMHO the only correct answer you should consider here is from ..(drum roll)

....u3b3rg33k Congradulations !
Reading it was like reading from a technical manual but better. He also added just enough real world view words to bring attention to the important details .
Smart man,we need to pay attention to his posts.
My posts do not reflect the opinions of this forum or its staff and should only be considered as my own opinion.!
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