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#4756015 - 05/13/18 03:03 PM Oil Consumption by Design
NICAT Offline


Registered: 04/05/18
Posts: 45
Loc: Azerbaijan
Some engines, such as volkswagen engines, are famous for consuming oil by design. As much as 1 liter per 1000 mile smile
My question is, does this theoretically mean less ring tension, thicker oil film at the cylinder wall, thus less wall and piston rings wear ?

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#4756070 - 05/13/18 04:25 PM Re: Oil Consumption by Design [Re: NICAT]
danez_yoda Offline


Registered: 07/18/09
Posts: 443
Loc: texas
Ive seen some high mileage engines with the original hone marks still in the cylinder walls. I dont piston wear is not a problem within warranty period. There must be another reason. The race community burns some oil to make more hp. I wonder if this is what they are doing.

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#4756147 - 05/13/18 05:48 PM Re: Oil Consumption by Design [Re: NICAT]
skyactiv Offline


Registered: 03/02/13
Posts: 4279
Loc: The Midwest
My wife owns an Audi and I own a VW Golf GTI. I need to add 1/2 a quart at the 4K mile mark and I change the oil every 5K miles.
My wifes Audi doesn't consume enough oil to make it worth adding.
I have heard some engines consume oil by design. Sounds silly but who knows?
I'm a semi mechanic and another much older mechanic told me some engines have soft piston rings that seal great
but wear out faster and some engines have harder piston rings that last longer but don't seal as well.

Years ago when I was building a small block Chevy, he told me the cheap Hastings piston rings are great for 60K! thousand miles
and the engine will start burning oil.

Click on the piston rings and learn something:
https://www.hastingspistonrings.com/aftermarket
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#4756503 - 05/14/18 05:50 AM Re: Oil Consumption by Design [Re: NICAT]
Johnny2Bad Offline


Registered: 05/20/13
Posts: 1721
Loc: Saskatchewan, Canada
I think pretty much every modern (post emissions-era) engine burn oil "by design" because it's mandated that oil blow-by can't vent to the atmosphere. A typical emissions setup has the PCV valve connected by a hose to the intake, where blow-by gas (oil vapour from the bottom of the crankcase) burns with the intake charge.

As any internal combustion engine will have pressure and temperature variations that are going to create blow-by gases; something has to be there to take care of it. Pre-emissions engines just vented it to the atmosphere (oil "breathers" on the intake valve cover(s) ) or going back to the 50's and earlier just let it drip onto the ground.

You can alternately vent the blow-by gas to a catch can, racers do this, but that means emptying the catch can periodically. No OEM is going to make owners do that.
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#4756506 - 05/14/18 05:58 AM Re: Oil Consumption by Design [Re: NICAT]
Shannow Offline


Registered: 12/12/02
Posts: 39421
Loc: 'Stralia
Originally Posted By: NICAT
Some engines, such as volkswagen engines, are famous for consuming oil by design. As much as 1 liter per 1000 mile smile
My question is, does this theoretically mean less ring tension, thicker oil film at the cylinder wall, thus less wall and piston rings wear ?


Cart horse inversion...

Low tension rings are to reduce drag, not wear, and oil consumption is (often) a result...which manufacturers then try to pass off 1qt/1,000 miles as "normal"...then when it's too bad, they add a dipstick with an altered "normal range" so it doesn't look so bad...then mandate lower P to protect emissions control devices on the ones that are bad, but now "normal".

No-one is purposely designing oil consumption IN to an engine (except for e.g. Mazda Rotaries). Their designs are causing increased oil consumption for other factors.

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#4756517 - 05/14/18 06:23 AM Re: Oil Consumption by Design [Re: NICAT]
Eddie Offline


Registered: 12/07/03
Posts: 9484
Loc: Florida, Cape Coral
My last 6 engines which were sold at 100,000 + miles never used more than 4 oz of oil in a 6,000 mile OC. Saab 2.0/Jeep 4.0/Subaru 2.5L/ Mazda CX7 and now my Mazda 2.5 at 42,000 miles. I think those engines were better engineered. Ed
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#4756522 - 05/14/18 06:28 AM Re: Oil Consumption by Design [Re: Eddie]
Shannow Offline


Registered: 12/12/02
Posts: 39421
Loc: 'Stralia
Better broken in I think.

Modern designs are all standard out of the box fit, not select fit like a '57 Chev was, or a 1970s Rolls Royce.

As a result, every engine is on average...well average in the fleet.

You can get an engine with tolerance stack up that makes it a burner, or marginally too tight (friction wise).

Only variable that you have in an "average" engine is to break it in properly.

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#4756535 - 05/14/18 06:39 AM Re: Oil Consumption by Design [Re: NICAT]
ShieldArc Offline


Registered: 03/16/13
Posts: 17
Loc: Ne
I'm still wondering why the 8.1 in my 2001 3500HD has used 1qt every 750 mi since new no matter what oil I put in it.

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#4756569 - 05/14/18 07:11 AM Re: Oil Consumption by Design [Re: ShieldArc]
supton Online   content


Registered: 11/09/08
Posts: 11716
Loc: NH
Originally Posted By: skyactiv
My wife owns an Audi and I own a VW Golf GTI. I need to add 1/2 a quart at the 4K mile mark and I change the oil every 5K miles.


Why bother adding? Is it at the add level, or will be soon at the add level? not saying it's a waste of oil, just not sure it's worth the effort. [I used to have a Saturn, got to the point where I'd add a qt around 2k, then at 3k it was a qt low again--so I'd just have it changed. I tried to time it to save on oil. But perhaps not the best automotive example.]

Originally Posted By: ShieldArc
I'm still wondering why the 8.1 in my 2001 3500HD has used 1qt every 750 mi since new no matter what oil I put in it.


Seems high, but, those were big cylinders. Lots of surface area for those rings to scrape. Not sure it's linear, but at 8.1L it's four times the size of the "standard" 2L I4. So, waving my hands a bit, 4x the oil consumption seems plausible. If so, be glad that a qt every 400 miles wasn't deemed acceptable by the OEM!
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#4756589 - 05/14/18 07:25 AM Re: Oil Consumption by Design [Re: NICAT]
SonofJoe Offline


Registered: 07/23/16
Posts: 1052
Loc: Europe
IMO, the 'all engines consume oil' thing is a fraud practiced by certain OEMs. They figured out decades ago how to adequately seal the combustion chambers from the rest of the crankcase (and by 'adequately', I do not mean completely). The problem is that that level of sealing comes at the cost of fuel economy. As Shannow said above, one of the easiest & cheapest things an OEM can do to improve fuel economy is move to thinner, low tension rings. I don't know for sure but I suspect some have also been increasing the bore to piston side clearance. Of course all of this 'removal of resistance to flow' makes it easier for blow-by gas to get passed the pistons.

Now superimpose on this to a shift to higher compression ratios (for fuel economy or in the case of Turbochargers, performance), higher Noack oils (as a result to moving to thinner, fuel economy oils) and you get the potential for more engine oil to be routed around the PCV system and burnt. The effects of this progressively worsen as the engine ages. So it's a case of OEMs trading (on your behalf) short-term economy & performance credits with medium term engine problems (which might not surface until you're out of warranty). Unsurprisingly, they are somewhat coy about fessing up to this but it is definitely the game that's being played here.



Edited by SonofJoe (05/14/18 07:28 AM)

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#4756592 - 05/14/18 07:29 AM Re: Oil Consumption by Design [Re: NICAT]
OVERKILL Offline


Registered: 04/28/08
Posts: 36206
Loc: Ontario, Canada
BMW went through this with the S62 and that was part of the reason for the spec for 10w-60, to help control consumption. The pre 03/00 engines could consume obscene amounts of oil and it was "par for the course" as per BMW. The post 03/00 engines had greatly reduced consumption due to updated rings, mine was reasonably good, only consuming ~1L/8000Km IIRC. One of the cars I looked at when I was shopping was a '99 that drank 1L/1000Km.
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#4756655 - 05/14/18 08:28 AM Re: Oil Consumption by Design [Re: NICAT]
KrisZ Online   happy


Registered: 12/23/06
Posts: 7401
Loc: Toronto, Canada
If this continues I see people believing more and more that oil consumption where you need to add oil between OCIs is normal. After all the engineers know best.
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2015 Dodge Grand Caravan-21k miles.
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#4756748 - 05/14/18 09:58 AM Re: Oil Consumption by Design [Re: NICAT]
Whimsey Online   content


Registered: 12/22/02
Posts: 4039
Loc: The Garden State
I guess I got lucky. Our 1996 Zetec 2L Contour even at 115,000 mi still doesn't use any really measurable amount of oil in even a 8,800 mi OCI. Our 195,000 mi 2005 4.6 V-8 Explorer again doesn't use any really measurable oil in a 9,000 mi OCI. Even our 2017 Explorer with the 2.3 EB doesn't use any really measurable amount of oil in even a 7,000 mi OCI. Low tension piston rings are suppose to help with gas mileage but increase oil usage I heard. And with our 2017 Explorer there doesn't appear to be enough measurable fuel diluting to the oil to keep the dip stick level up per my two UOA's.

Whimsey

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#4756810 - 05/14/18 10:50 AM Re: Oil Consumption by Design [Re: NICAT]
ZeeOSix Offline


Registered: 07/22/10
Posts: 17482
Loc: PNW
Only engine I've heard of that was designed to burn oil were the Mazda Wankel. They have an oil injection pump that takes oil out of the sump and injects it into the rotor chamber for lubrication of all the side and rotor tip seals. I had two RX-7s and they used about a quart every 3000 miles, by design.

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#4756912 - 05/14/18 12:22 PM Re: Oil Consumption by Design [Re: NICAT]
KrisZ Online   happy


Registered: 12/23/06
Posts: 7401
Loc: Toronto, Canada
All engines have to consume oil, all of them, but the normal amount, on a healthy engine with properly broken in and not stuck piston rings, will not be noticeable on the dipstick or the change in the level should be minimal.

For engines over 100k miles, if the oil level stays between the min and max lines for the entire OCI, I would consider that normal as well.

And low tension piston rings are nothing new, it's just something people like to repeat to convince themselves and others that it is normal. You repeat it enough times and it becomes the truth.
_________________________
2015 Dodge Grand Caravan-21k miles.
2006 Mazda 3-155k miles

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