Is oil consumption always a bad thing?

[buster]

I posted this in another thread (SSO/14k mile thread).

I think mostly it is just an inconvenience (having to add oil occasionally). Only car owners seem to be upset by oil consumption. OEM's are not. In fact, 1 qt per 1000 miles is acceptable.

I think most peoples' analysis of "why engines burn oil" is based on the false idea that an engine shouldn't burn any oil and if it does burn some oil then something must be wrong with it. Thoughts? The Toyota I had burned 1qt per 3k miles from day 1 and ran like new with 180,000 miles.

I was told/read that most high output engines will always use some amount of oil as keeping the top rings lubricated at high loads and high RPM is impossible without loosing some oil past the rings.

I've read that many engines have very aggressive cylinder wall finishes to maintain oil on the cylinder walls to keep the rings lubricated in high power levels. With that you can often end up with high oil consumption.

BMW had oil consumption issues in their M series engines. They actually replaced engines that failed from oil starvation due to the high rate of oil consumption that was apparently normal due to the aggressive cylinder wall finish and low tension ring pack.

So I'm not sure what is the right answer as far as whether it's ok or normal for some engines to use oil, or whether it's an engineering flaw. I want to say that no engine should burn oil under ideal circumstances.

Have any of you had cars that burned oil from day one and lasted a long time?

 

[cmhj]

Originally Posted By: buster


Have any of you had cars that burned oil from day one and lasted a long time?


Yup,

Wife had a 95 Saturn 1.9 L? that burned oil from day one. After 200K miles the usage only increased slightly and mileage stayed almost as it was from new.

Some oil usage is no big deal.

 

[Hokiefyd]

Buster, it looks like your post could have come from the writings on a few Cadillac sites about Northstar engines. They have a very aggressive cylinder hone pattern that promotes oil retention on the walls -- that that also means oil consumption. Modern engines also utilize low-tension rings which tend to promote some added consumption.

Back in the day, if an engine "used no oil", it was a good design. But you also had to rebuild engines after 100,000 miles, and had to bore the cylinders and ream the ridge off the top. Many of today's engines run for half-a-million miles, all while using a quart or two every oil change.

Two benefits: first, if the oil consumption is due to good retention on the cylinder walls (and not from stuck rings or something like that), you know your cylinders are well-lubricated. Second, you obviously get a nice spike in your oil additives when you dump in a new quart.

 

[buster]

Thanks Jason. Yes, that was one source I had read about it. Thanks for the explanation.

Engines are lasting longer then they ever have and putting out more power as well.

 

[Gary Allan]

Like has been expressed here ..I think it's a "pride quotient" point. Defective engines consume oil, my engine consumes none since it's not defective. The person never encountered or owned an engine that routinely consumed oil as a design characteristic.

I can't say that I "enjoyed" oil consumption (if 3 out of 5 suffer from diarrhea, do the others enjoy it?

)but ..it never bothered me.

 

[strombony]

My mechanic has always told me that all vehicle manufacturers will tell you a veh can use a half quart between oil changes, but he doesn't believe it and thinks that if a vehicl is put together properly, it shouldn't.

 

[e40]

Originally Posted By: cmhj
Wife had a 95 Saturn 1.9 L? that burned oil from day one.


Same here - my ex had a 96 Saturn that would need at least a quart or two between intervals.

 

[Eddie]

Stating that consumption of one quart per 1000 miles is normal is ludicrous in a modern daily driver. I never had an engine that consumed more than a few OZ in 5,000 miles.

 

[buster]

Originally Posted By: Eddie
Stating that consumption of one quart per 1000 miles is normal is ludicrous in a modern daily driver. I never had an engine that consumed more than a few OZ in 5,000 miles.


Agree, 1qt per 1k miles is excessive. However, it kind of shows you that some oil consumption is perfectly normal and acceptable.

 

[XCELERATIONRULES]

+1
I've never had a low mileage vehicle that used oil.

 

[Bamaro]

My 02 SE-R burned 1QT/1500 miles from day one and Nissan said that was not a problem

 

[John K]

I had a 01 PT Cruiser that burned oil from day 1, usually a quart between 1100-1500 miles. I tried various oils, viscosities, dino, synthetic and never noticed a difference. Also had a 77 Volare slant 6 that burned oil from day 1, about 1 qt/1000 miles. I think that is an excessive amount, but it gives manufacturers wiggle room. I remember hearing Alfas and others way back (60s) that it was considered normal to burn oil. I do not understand how an engine can not burn some oil and not suffer from wear of rings.

 

[Kestas]

Twenty years ago manufacturers started lowering the tension on the piston rings in an effort to reduce friction and raise gas mileage efficiency in their vehicles. One consequence was a slight increase in oil consumption. But I never noticed it on the vehicles I took care of.

Though burning one quart every 1000 miles is acceptable, it is not normal.

It's acceptable in the sense that no action is needed except for more diligence in maintaining the oil level. Once it starts burning one quart every 500 miles (the threshhold in many publications), then drastic action must be taken to remedy the situation since it starts fouling plugs, converters, and other such problems.

In the sense that it's your personal vehicle, it's unnaceptable since it indicates either poor oil maintenance from the first owner, excessive eninge wear, or a defect in the engine.

 

[John_K]

Originally Posted By: XCELERATIONRULES
+1
I've never had a low mileage vehicle that used oil.


My wife's Sonata doesn't use a drop. My Dakota has used a little since brand new.

John

 

[Junior]

A quart every 3-5000 miles has never bothered me. 1 quart per 1000 when new would sigal a problem to me. But that is just me.

Not an atomotive engine but the diesel engines in the offroad equipment my company produces will use a gallon of oil in 50-100 hours when new. (sump capacity of 6-7 gallons) Never been a problem and considered normal. For this particular application we measure oil consumption as a percentage of fuel used.

 

[Eddie]

a quart per 1000 miles suggests something is wrong with that engine (worn parts, worn-out or bad design). Dealers use it as an excuse. GM started that idea back in the 50s when a big production run of their engines had oil control rings installed upside down. Seems it was picked up as an excuse by some other manufactures but, not all.

 

[HTSS_TR]

I currently have 3 cars:

'94 LS400 with 202k miles use 1/2 quarts every 4k miles, 6-7k OCI's with dino or 10-12k OCI with synthetic. This did not use oil for the first 8 years/100k miles, after that it started to use oil at a rate of 1/2 quarts per 6k miles and now a little more.

'00 E430 with 98k miles did not consume any oil with 11-13k mile OCI's with synthetic.

'04 S2000 with 29k miles never added oil with 6m/3k OCI's with dino.d

Ideally, no car should consume more than 1/4 quarts every 5k miles for the first 100k miles.

 

[addyguy]

Originally Posted By: Eddie
a quart per 1000 miles suggests something is wrong with that engine (worn parts, worn-out or bad design). Dealers use it as an excuse. GM started that idea back in the 50s when a big production run of their engines had oil control rings installed upside down. Seems it was picked up as an excuse by some other manufactures but, not all.


GM's relied on that excuse A LOT over the years - the Vega engine, and the Saturn 1.9 are good examples where it saved them from warranty work, or a massive recall.

Thankfully, my 2.2 OHV Cavalier only burns about 1/4 quart every 5k miles....

 

[buster]

Break-in procedure and fuel dilution are also factors.

 

[ViragoBry]

I don't think I'd ever find 1qt / 1000 miles to be an acceptable amount of consumption on a car with less than 100K miles. I tend to judge all my cars on the behavior of my first and second Civic Si's, neither of which used a drop in 3000 miles. As hard as those two cars were driven, none of the rest of my cars have any excuse to consume oil...and thankfully, none of them have. I gave my first car some leeway, since it was a 1978 Monza with the Iron Duke 2.5, with 55,000 miles on it. I considered it a miracle that it only used 1/2 a quart in 3000 miles.

The inconvenience of having to add oil periodically isn't really the issue with me. Oil contamination of the exaust and emissions equipment is my point of contention.

RX-8 owners, I can only assume have to carry oil with them wherever they go.