Facts about oil consumption

[Falcon_LS]

This is out a '02 Lexus ES owner's manual. Although quite general in context, and things we already know, I found it interesting and I thought I'd share:

Originally Posted By: Lexus Owner's Manual
FACTS ABOUT ENGINE OIL CONSUMPTION

Functions of engine oil
Engine oil has the primary function of lubricating and cooling the inside of the engine, and plays a major role in maintaining the engine in proper working order.

Engine oil consumption
It is normal that an engine should consume some engine oil during normal engine operation. The causes of oil consumption in a normal engine are as follows.:

• Oil is used to lubricate pistons, piston rings and cylinders. A thin film of oil is left on the cylinder wall when a piston moves downwards in the cylinder. High negative pressure generated when the vehicle is decelerating sucks some of this oil into the combustion chamber. This oil as well as some part of the oil film left on the cylinder wall is burned by the high temperature combustion gases during the combustion process.
• Oil is also used to lubricate the stems of the intake valves. Some of this oil is sucked into the combustion chamber together with the intake air and is burned along with the fuel. High temperature exhaust gases also burn the oil used to lubricate the exhaust valve stems.

The amount of engine oil consumed depends on the viscosity of the oil, the quality of the oil and the way the vehicle is driven.

More oil is consumed under driving conditions such as high speeds and frequent acceleration and deceleration. A new engine consumes more oil, since its pistons, piston rings and cylinder walls have not become conditioned.

When judging the amount of oil consumption, keep in mind that the oil may have become diluted, making it difficult to judge the true level accurately. For example, if a vehicle is used for repeated short trips and consumes a normal amount of oil, the dipstick may not show any drop in the oil level at all, even after 1000 km (600 miles) or more. This is because the oil is gradually becoming diluted with fuel or moisture, making it appear that the oil level has not changed.

The diluting ingredients evaporate out when the vehicle is then driven at high speeds, as on an expressway, making it appear that oil is excessively consumed after driving at high speeds.

Importance of engine oil level check
One of the most important points in proper vehicle maintenance is to keep the engine oil at the optimum level so that oil function will not be impaired. Therefore, it is essential that the oil level be checked regularly. Lexus recommends that the oil level be checked every time you refuel the vehicle.

 

[KrisZ]

Quote:
One of the most important points in proper vehicle maintenance is to keep the engine oil at the optimum level so that oil function will not be impaired. Therefore, it is essential that the oil level be checked regularly. Lexus recommends that the oil level be checked every time you refuel the vehicle.


I think this part is really important, and a lot of people ignore it.

I had a friend that used to brag that his car only gets the best synthetics (Royal Purple) and when I asked how often he changes his oil, his reply was, when the little oil light comes on (he was talking about the oil pressure idiot light).

 

[Quattro Pete]

Do they specify anywhere what amount of oil consumption is considered abnormal?

 

[Falcon_LS]

I completely agree.

A lot of my friends do not even know how to check their oil.

Originally Posted By: KrisZ
...when the little oil light comes on (he was talking about the oil pressure idiot light).

Sorry, I couldn't resist not laughing at that!

 

[MONKEYMAN]

What about worn out valve guide seals and gummed up oil control rings that no longer wipe oil? It seems that will affect oil consumption more then a new engine?

 

[Gary Allan]

Originally Posted By: Falcon_LS


Sorry, I couldn't resist not laughing at that!

Oh, it's very funny. It's just that it's dark comedy.

 

[ryland]

My friend who has a rx-8 only will use conventional in his rx-8 and other cars because mazda says according to him that the rotary engine meters a small amound of oil with each revolution (much like a two stroke but at smaller incriments) and that synthetic oil since its designed to resist burnoff leaves a residue when burned and that dino burns much cleaner. So just like this says normal piston engines burns small amounts as well so he refuses to use synthetic. While I dont agree with him thats an intristing theory.

 

[lexus114]

Originally Posted By: KrisZ
Quote:
One of the most important points in proper vehicle maintenance is to keep the engine oil at the optimum level so that oil function will not be impaired. Therefore, it is essential that the oil level be checked regularly. Lexus recommends that the oil level be checked every time you refuel the vehicle.


I think this part is really important, and a lot of people ignore it.

I had a friend that used to brag that his car only gets the best synthetics (Royal Purple) and when I asked how often he changes his oil, his reply was, when the little oil light comes on (he was talking about the oil pressure idiot light).

Uh,thats a little over kill isnt it??

 

[Warstud]

Qoute: "A new engine consumes more oil, since its pistons, piston rings and cylinder walls have not become conditioned".

I did not know that! Is this for the first say 500-1000 miles or what?

 

[Falcon_LS]

Originally Posted By: Quattro Pete
Do they specify anywhere what amount of oil consumption is considered abnormal?


Not really. Just possible causes of oil consumption, how to read the dipstick, what type of oil should be used and some stuff on the API. Although this is what's printed in my Montero's owner's manual:

Originally Posted By: '00 Mitsubishi Montero Owner's manual

Engine oil
All engines consume a certain amount of oil during normal operation, and engine oil consumption is greatly influenced by payload, engine speed, etc. Therefore it is important to check the oil level at regular intervals or before starting a long trip.

(section on how to check your oil level)

If the oil level is below the specified limit, remove the cap located on the cylinder head cover and add enough oil to raise the level to within the specified range. Do not overfill, and be sure to only use oil of the recommended quality and appropriate viscosity. Avoid mixing different brands of oil together if possible. The use of any oil additives is strictly not recommended, as they may reduce effectiveness of additives already present in the engine oil.

 

[saberz]

All I ever heard was just straight up NO to synth in Rotaries, never new why. My cousin has an emerald green RX7 and maintains it using dino as well.


Reading about it more in-depth it seems Mazda was using an "unnamed" synthetic in a race and it had caused engine failure. Rather than name the company and synthetic brand and face a lawsuit they all together banned the use of synthetic.

From my reading on I found that only RedLine oils are acceptable for use in the Rotory engine and only RedLine.

 

[demarpaint]

Actually a very good explanation. A engine that doesn't use any oil at all is not necessarily in better shape than an engine that uses some oil. Many people use oil consumption as an indication of an engines condition, it really means nothing if consumption is slight.

 

[Falcon_LS]

Originally Posted By: Warstud
Qoute: "A new engine consumes more oil, since its pistons, piston rings and cylinder walls have not become conditioned".

I did not know that! Is this for the first say 500-1000 miles or what?


Section on break-in says 1,600 km/1,000 miles.

 

[XS650]

Originally Posted By: Quattro Pete
Do they specify anywhere what amount of oil consumption is considered abnormal?


The acceptable amount depends on whether it's warranty claim or not.

 

[StevieC]

My UOA's always come back showing no moisture/water, no glycol and no fuel dilution and my oil doesn't move on the dipstick even after a 15K KM (9K mile) OCI. I have 200K KM (120K miles) on my engine and it doesn't use any oil.

Guess I'm lucky...

 

[Spector]

Depends on the engine, driving conditions oil etc. I have one that seems to use none other uses a quart every 7000 or so amd more if interstate conditions. All engines use oil, just a question of how you define usage ( some say it does not use if still in the hash marks when obviously it has)and over what OCI

 

[StevieC]

Interesting thread to say the least... Thanks to Abdulla (Falcon_LS) for posting!

 

[Falcon_LS]

No probs!

 

[ADFD1]

Dad said normal oil use was a qt/1000 miles, according to most car mfg's, and a lot of dealerships used that as a cut off. Then when people came in using a qt every 750 miles they considered that normal LOL. No one really knows what normal use is, but as a rule of thumb 1000 miles seemed to be the magic number for acceptable oil use. YMMV

Good Info Falcon.........Thanks!

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[txrhino]

I run 13000-15000 miles between changes on 6.0L VMax, never need to add.