Exploring The Causes of Excessive Oil Consumption

wayoflife

wayoflife

Administrator
Staff member
So, I was scanning through my news feed this morning and came across this article by Alex Steele of Truck Trend regarding excessive oil consumption on modern engines. For those of you who aren't familiar with the problem, you might find it to be a good read.

Shop Class: Exploring The Causes of Excessive Oil Consumption
Alex Steele, Truck Trend Editors

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It’s not just the mega-mileage ’75 F-100 blowing blue smoke out the tailpipe any more. Over the past decade a large number of low-mileage, late-model car and truck engines have been consuming excessive amounts of motor oil. The mechanical failures vary, but the root cause seems to be each manufacturer’s hurry-up need to meet EPA fuel economy and emissions requirements.

Yes, every four-stroke engine does normally burn a small amount of oil.

Before we get into the technical aspects of oil consumption, let’s look at how much is too much. Most manufacturers publish what we consider “cover-your-butt” specifications – commonly one quart burned every 1,000 miles being the normal threshold. Now let’s think about this. With recommended oil change intervals increasing from the old-faithful 3,000 miles and getting closer to 7,000, you could be adding 6 or 7 quarts of oil between services. Say your engine has a 5-quart oil capacity, you’re now buying up to 12 quarts per service, and all that extra oil is burned up and discharged into the atmosphere. Not to mention the carbon buildup in the combustion chamber and back of valves, rendering further harm to the engine’s performance and lifespan.

These oil consumption specs seem ridiculous, and thankfully most, but not all, manufacturers and dealership service departments will perform a repair before oil consumption reaches that degree.

Typical entry points of oil into the combustion chamber are past the piston rings and valve guides. Each piston utilizes rings, which are spring-loaded against the cylinder wall. These piston rings seal the high pressure in the combustion chamber, from the motor oil flying around inside the crankcase.

Click on the link below to read the whole article.
http://www.msn.com/en-us/autos/owne...consumption/ar-BBrL3Jx?ocid=spartanntp#page=1
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Guascone

Guascone

Member
The big oil consumption is directly ralated to usage of the low viscosity oil ...
To reduce the friction on the cranck mechanism in order to have lower fuel consumption one of the most efficent solution is to adopt the low viscosity oil.
This generate a lot of blowbye . Also the piston ring have a smaller radial force always to have smaller friction but this is the route couse of the permeability of the system...
I hope that my english is enought correct to be comprenisble...
 
Christarp

Christarp

Member
Guascone said:
The big oil consumption is directly ralated to usage of the low viscosity oil ...
To reduce the friction on the cranck mechanism in order to have lower fuel consumption one of the most efficent solution is to adopt the low viscosity oil.
This generate a lot of blowbye . Also the piston ring have a smaller radial force always to have smaller friction but this is the route couse of the permeability of the system...
I hope that my english is enought correct to be comprenisble...
Click to expand...

Sounds good enough for me!

Also yeah thanks for posting this article up, I kind of figured this was the case but it's nice to see a more in depth article.
 
2nd.gunman

2nd.gunman

Caught the Bug
My experience has been that the new cars that have oil consumption problems are typically not serviced at the correct intervals or the mechanic/owner has used the wrong oil
 
wayoflife

wayoflife

Administrator
Staff member
2nd.gunman said:
My experience has been that the new cars that have oil consumption problems are typically not serviced at the correct intervals or the mechanic/owner has used the wrong oil
Click to expand...

I don't know. Maybe I just don't know what I'm doing but I think I'm using the right oil and maintain my Jeeps myself. I never had any oil consumption problems on my old 3.8L and I had well over 100,000 miles on it before swapping in an LS. My new 3.6L has about 85,000 miles on it and it's been burning about a quart to 2 quarts every 1,000 miles (depending on the kind of driving I do) for a while now.
 
martinzusmc

martinzusmc

New member
I installed an Moroso oil catch can on both PCV lines and was surprised how much oil it had in it just after a 500 mile drive.
 
C

Chad

New member
Great article Eddie, thanks. Definitely gives me something else to think/worry about when it comes to my Jeeps maintenance and upkeep, especially just hitting 95k miles.
 
B

Bingobelle

Member
wayoflife said:
I don't know. Maybe I just don't know what I'm doing but I think I'm using the right oil and maintain my Jeeps myself. I never had any oil consumption problems on my old 3.8L and I had well over 100,000 miles on it before swapping in an LS. My new 3.6L has about 85,000 miles on it and it's been burning about a quart to 2 quarts every 1,000 miles (depending on the kind of driving I do) for a while now.
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That sound insane much to me.

My 3,6 penta does not need one single drop of extra oil between the 7 500 miles oil change. My engine now has 60 000 km on the odometer. ( about 37 000 miles )

Before I had a toyota rav4 and same with that engine, not a single drop of oil extra needed between oil service. that engine had gone about 110 000 miles when I sold it. Never had to refill.
 
wayoflife

wayoflife

Administrator
Staff member
Bingobelle said:
That sound insane much to me.

My 3,6 penta does not need one single drop of extra oil between the 7 500 miles oil change. My engine now has 60 000 km on the odometer. ( about 37 000 miles )

Before I had a toyota rav4 and same with that engine, not a single drop of oil extra needed between oil service. that engine had gone about 110 000 miles when I sold it. Never had to refill.
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I agree, totally insane. Unfortunately, I'm well out of warranty and even if I still were covered, I know I would just be told that it's normal. :rolleyes2:

Being that I have so many miles on the motor, I just deal with it for now. If I drive slower and stay off the RPM's, the consumption is a lot less.
 
Christarp

Christarp

Member
2nd.gunman said:
My experience has been that the new cars that have oil consumption problems are typically not serviced at the correct intervals or the mechanic/owner has used the wrong oil
Click to expand...

It was only after I tracked how much oil my jeep was burning that I decided to switch from full synthetic to conventional. My oil has been serviced perfectly on time every time by me, so I wouldn't say it's that.

The main reason I switched from full synthetic to conventional is that I simply can't afford to put a new quart of full synthetic in my jeep every 600 miles. Fortunately I can afford to put in $2.50 worth of oil in every 600 miles, so for now I'm just dealing with it.
 
J

Jeepnoub

New member
I think a portion of the issue can go towards mass production and stacking tolerances. Today's engines are built with pretty tight tolerances and clearances.

Imagine a engine on and assembly line. Each worker puts his parts on that meet his specific parts specs, then goes down to the next guy and the same thing and so on. So instead of one guy building everything 10, 15, 20 people build an engine and as long as all their parts line up its good to go. No one is to know how tight or loose the overall package is.

Now, not all engines are build in this fashion but you can get the picture.
 
swampdog

swampdog

New member
I think another aspect to think of is that many of us have re-geared our rigs, which obviously increases the RPM at any given speed. In my mind, the percentage of raise in RPMs would directly correlate to an equal percentage increase in oil usage due to gapping / blowby. Agree / disagree?
 
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2nd.gunman

2nd.gunman

Caught the Bug
wayoflife said:
I don't know. Maybe I just don't know what I'm doing but I think I'm using the right oil and maintain my Jeeps myself. I never had any oil consumption problems on my old 3.8L and I had well over 100,000 miles on it before swapping in an LS. My new 3.6L has about 85,000 miles on it and it's been burning about a quart to 2 quarts every 1,000 miles (depending on the kind of driving I do) for a while now.
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As I said that has been my experience after investigating service history and getting oil samples lab tested but was a generalisation.

I've seen a number of exceptions twhich were caused by design or manufacturing faults like when Mercedes Benz got the DPF regen calibration wrong on the 642 V6 in the vito resulting in severe oil dilution and then consumption within 15k kms. Or the first batch of Holden Commodores fitted with the LS1 which had a piston ring issue requiring every one to have the engine rebuilt within 10k kms due to oil consumption.

My only experience with the 3.8 & 3.6 has been with my own jeep and a couple of others which haven't had any oil consumption issues but I am aware others have had issues such as yourself.
 
Sudz

Sudz

New member
I don't understand all these oil consumption problems with newer engines.

I had a '71 Olds Cutlass that I bought in '74. I literally put 249,000 miles on that car before I junked it. (rusted out body) - never burned a drop of oil and the trans shifted great right up to the end.

The motor & trans were all original. My current ZJ 4.0 motor runs great @ 200,000+ miles. It doesn't burn a drop of oil.

I put a head gasket on it last year. Cylinder walls still had the honing marks from the factory and no carbon build up on the pistons or valves.

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