"All engines burn some oil." Really?

Status
Not open for further replies.
Joined
Jan 21, 2011
Messages
2,677
Location
California
If this has been discussed before, please post a link to the thread(s) and close this one. Searched but did not find.

I understand the concept of the cylinder being lined with a very thin layer of oil, which is partially burned off during the combustion process and the oil is replaced on the next piston stroke. The amount burned will differ between vehicles and even between different examples of the same engine, and depending on various factors. Also oil has some volatility or "burnoff" during a service interval which would (should) also show a lower dipstick reading as oil vapor is sucked through the PCV system and burned.

But... both of my road vehicles have the same dipstick reading, every time, throughout an oil service interval. Even at the end of a 7500-mile oil run, the dipstick level has not changed much if at all, I mean maybe it drops 1mm at the very most which is practically nothing. I am definitely not complaining! I just want to understand why the reading is consistent if the oil is being burned in the combustion chamber and also vaporizing. Maybe fuel dilution is making up for the lost oil volume? I know many of my friends' vehicles "never use any oil." I haven't done an oil analysis yet and I don't plan to since there are no issues. Just curious. Thanks!
 
Of course all engines use oil. Some more than others, with a dipstick to monitor. The size of the oil pan can make a difference in how fast it appears to drop too.
 
I have ownd over 20 vehicles that never used a noticeable amount of oil except one, a 2006 Forester. Used 1/2 quart every 4k miles. But, Boxer motors are known oil users.
 
Last edited:
I think a more complete statement may be as follows:
All engines have the potential to burn oil over their lifespan. And the amount of oil that is consumed may increase or decrease over that lifespan.

There are many inputs that influence oil consumption. Some inputs are direct influences and others require multiple variables to result in an oil consumption condition. It's just not as easy as stating 'x' therefore 'y'.

Low tension piston rings.
PCV system design and conditions.
Oiling system design.
Oil fill level.
Piston ring condition and wear over time.
Cylinder wall condition and wear over time.
Driving conditions and use and abuse by the operator.
Oil viscosity.
Preventative maintenance schedule.

Just to mention a few of the input varaibles.
I'm sure others could add quite a few more...
 
Last edited:
If you don't lose more that one qt per oci,"It doesn't burn any oil". The only ones the burn oil are the ones that need a qt during the oci.
 
Originally Posted by danez_yoda
If you don't lose more that one qt per oci,"It doesn't burn any oil". The only ones the burn oil are the ones that need a qt during the oci.



+++ 100% correct
 
The scraper rings on the pistons are not 100% efficient. Therefore, all engines will consume some oil. That amount may be too small to notice. Gasoline and other contaminants in the oil could mask small oil consumptions.
 
I believe the oil film on the rings to liner can be as little as 1 micron under ideal conditions, so it's not like you're burning a tankers worth of oil each stroke.

My car doesn't burn anything I can discern by eyeballing the not so accurate dipstick. I know some is being burnt but just how much dunno...certainly not enough to worry me any.
 
Last edited:
Originally Posted by redbone3
The scraper rings on the pistons are not 100% efficient. Therefore, all engines will consume some oil. That amount may be too small to notice. Gasoline and other contaminants in the oil could mask small oil consumptions.


That's exactly what happens. Propane and natural gas engines don't contaminate the oil nearly as much as gasoline/diesel and the very same engine will use more oil on propane than it will with gasoline. In fact, manufacturers of propane fueled engines will carefully note that oil consumption is directly proportional to engine load. This is not unlike aircraft piston engines, where oil consumption is related to engine load.
 
If you live a place with much slow trafic and start/stop and a lot of cold starts and short trips the consumption is masked by condensation and fuel mixed in the oil, if one suddenly lets the car drive hard then it suddenly falls on the dipstick because condensation and fuel burn up when the engine gets to work hard
 
newer vehicles seem worse as noted by the parts listed manufacturers are TRYING to increase MPG while meeting the EPA!! on a similar note manufacturers are QUIETLY introducing dual fuel injection systems while NOT admitting the flaw with DI only that carbons the valves sooner or later depending on model + make!!! girlfriends 2.5L DI 2013 malibu was using some oil new with watery 5-20 but a change to 10-30 helped a while but by 60 thou it was a qt on a thou + getting worse + setting cat codes prolly from oil consumption, so she dumped the GM junk for a lo mile 18 optima, so far so good + a much better car overall in our opinion!!
 
Last edited:
Originally Posted by ToadU
Originally Posted by danez_yoda
If you don't lose more that one qt per oci,"It doesn't burn any oil". The only ones the burn oil are the ones that need a qt during the oci.



+++ 100% correct


-1

There are some that still do 3,000 mi OCIs; burning through a quart in 3,000 miles is "burning oil."
If it's indiscernable that any is being burned in your OCI via a dipstick, then say "it doesn't burn any oil."
 
I keep the judgement very simple. I fill the oil to the full mark on the dipstick. If it falls below that then the engine is either burning or leaking oil.

Unscientific yes but that's what I've gone by for 45 plus years of vehicle ownership.
 
Originally Posted by benjy
newer vehicles seem worse as noted by the parts listed manufacturers are TRYING to increase MPG while meeting the EPA!! on a similar note manufacturers are QUIETLY introducing dual fuel injection systems while NOT admitting the flaw with DI only that carbons the valves sooner or later depending on model + make!!! girlfriends 2.5L DI 2013 malibu was using some oil new with watery 5-20 but a change to 10-30 helped a while but by 60 thou it was a qt on a thou + getting worse + setting cat codes prolly from oil consumption, so she dumped the GM junk for a lo mile 18 optima, so far so good + a much better car overall in our opinion!!


That's what your rechargeable drill and a bunch of zip ties if for.......
 
comes back to scraper rings, located in the oil-control groove of each piston,
and whether or not the drain back holes are carboned up.
Just ask a Honda Civic owner. (well, one with more than 90k miles)
 
Originally Posted by Imp4


...Low tension piston rings.
PCV system design and conditions.
Oiling system design.
Oil fill level.
Piston ring condition and wear over time.
Cylinder wall condition and wear over time.
Driving conditions and use and abuse by the operator.
Oil viscosity.
Preventative maintenance schedule.

Just to mention a few of the input varaibles.
I'm sure others could add quite a few more...


I would add valvestem seals to that.
 
I've had everything from oil guzzlers to oil vegan's. It just depended on the car. I've also owned 4 Northstar's, the only time those don't burn oil is when they're all out. My '98 Corolla was also a guzzler, a common 1ZZ-FE issue.

That being said, my current Impala burns no oil at 180k, although it's had either full-syn or HM it's whole life. My 225k mile Marauder with the 4.6 (another known oil burner) didn't use more than half a quart every 5k.

Low tension rings are a big part of the issue. The Subaru FB20 is a perfect example. Those things eat a steady diet of 0W20 like it's going out of style. I don't care what anyone says, that engine is an oil burner. Every single one of them.
 
If you have multiple 15-25 year-old vehicles that don't use oil in 7K runs, you qualify for today's Gold Star Award.
Bravo..... please give us more details on your secret to success.
 
Originally Posted by MolaKule
Originally Posted by Imp4


...Low tension piston rings.
PCV system design and conditions.
Oiling system design.
Oil fill level.
Piston ring condition and wear over time.
Cylinder wall condition and wear over time.
Driving conditions and use and abuse by the operator.
Oil viscosity.
Preventative maintenance schedule.

Just to mention a few of the input varaibles.
I'm sure others could add quite a few more...


I would add valvestem seals to that.



Add
Valve cover leaks
Front and rear crankshaft seals
 
Status
Not open for further replies.
Back
Top