Oil Consumption, how to really figure it out?
 

Most people talk of quarts in a mileage sense. Well, I am thinking that we need to really see how are cars use oil.
There are many variables, such as engine size, rpms due to gear choices, steady state vs city driving etc etc.
What can we honestly due to figure out our oil consumption. I mean, if I tracked a car for an hour and used a quart after 250 miles, yet on the highway and I am cruising in OD till I hit 250 miles and I use no oil, what has changed?
I am thinking one thing tells us how we are doing with oil consumption, and that is compare it to fuel consumption.
I am no engineer, no mathematician, but if you get 10 mpg and use 1 quart of oil, then you get 20 mpg and use 1/2 quart, you will eventually see a trend.
ANyways, just my thought. Whats yours?

my car doesnt leak oil.

Okay, but I am referring to engine oil consumption, from rings being low tension(blow by), valve stems for us overhead valve stuff, etc etc.

it's fairly rare any more for oil control rings to fail. Most cars of age or mileage, will see wear in the valve seals and valve guides. In this case, you are going to see oil consumption in high vacuum situations like deceleration when the throttle valve is closed and negative pressure is between the cylinder and throttle. The vacuum will draw through the valve seals and pull oil into the combustion chamber.

oil viscosity is also going to play a huge role in this if you're running a 5w30, obviously you are going to consume more oil than if you were running 10w30 or a straight 30w. The 5w30 is going to get by the seals much easier than a straight 30 will. I haven't used any of them, but there are a few oils out there that are supposedly formulated for high mileage engines (75,000 miles [which doesn't seem like it's that high anymore TBH] ) and is supposed to reduce oil burn off.

When are you going to burn the most oil? Easy. Cold start.

While your engine has been sitting, oil has been leaking through your valve seals/guides and onto the valves. Open valves will allow oil onto the piston or cylinder wall. This oil will be burned off as soon as the ignition fires, resulting in white smoke behind the car.

You may think that at idle you're burning a lot, but it's not much compared to what's been getting into the cylinder overnight.

blah blah blah stfu and get to the point. right?


i think a more effective way to measure consumption would be quarts/operating hours. but since no one really times how long their engine has been running, it's just easier to put it in quarts/mile.

GM produced a couple million V8 engines from 1997 through 2002 or so that were all fitted with poorly performing oil rings.

Many of these engines would suffer ring flutter anytime they operated above about 4,000rpm - and with sustained higher rpm low load conditions can and do use oil at a rtae of 1 quart per 500 miles driven.

The fix was to replace the oil rings with appropriate new ones.

The catch is GM put most people off till their cars were out of warranty.

SOme really bad side effects for bigger (7l and up) V8's was trerrible cold start piston slap. This would result in guaged bores and when forced to, GM would replace these motors under warranty.

I had my 2001 (a June 2000 manufacture) LS6 replaced under warranty at 35,000 miles. Thats how long I had to battle GM to get them to pony up to their screw up.

I hadn't heard that one yet.

I know Mercedes was having a BITCH of a time with their V6 in the MLs losing their rings by 60K. In one case, the block itself was cast way too thin and the oil actually seeped through it. You could see light when shined from the other side of the block :shock:

BMW had a horrible problem with their M60 NikaSil blocks in the E34 530. The few engines that have lasted are dropping slowly but surely. Last i heard, BMW was buying the long block and the customers just had to pay the labor.

Every company has a rash of problems like that though at some time or another. Just the downfall of using humans to engineer things :bah: Keeps my job secure though :mrgreen: