why does oil 'disappear'?

[Kevin Hahn]

This test is going to enter its third year, which for the results seems abnormally long I am sure. I have only run the test in the late spring-early fall seasons to help minimize things like oil loss from cold starts (I should redo my valve stems because in the cold they contract, I get a little blow by, when the engine is warm I can rev it all I want without observing any oil burn off).


The point of the test is not to find a relationship between oil loss and the quality of oil filter, but to evaluate the performance of various oil filters for my application.


What started this was an observation of a confusing trend, the trend is not the foucs, and will not beomce the focus of my experiment, it is an extraneous phenomenon not and expected or studied outcome. I think a lot of the questions and answers have taken this experiment to be looking for a corrolation between oil loss and filters, this is false, I repeated my self to be perfectly clear.


For the record in the winter on average I loose about .7 qt every 3,000 miles do to blow by on cold starts.

 

[TR3-2001SE]

I just had a simular occurance with my engine. It has been burning about 1 quart every 1500-2000 miles which was an improvement over the 500 mile per quart before I starting using auto-rx. I changed the oil to a new oil delo 400 15w-40 from chevron 10w-30 and in 200 miles 1 quart disappeared. Now I have two spots on my driveway that tell me it leaked some of this oil. I am guessing the seals where cleaned and have to reseal as per the auto-rx web site. However they never leaked before. I could have an oil filter or plug leak which I will check tomorrow. Could either one of these be your situation ie leaky seal suddenly or leaky filter/plug.

 

[Kevin Hahn]

Haven't had an oil leak or a tell tale oil leak spot in about 2 years (that was a leaky rear engine seal).

Haven't had an oil leak since before the test started.

 

[White 03]

I think I now understand the question better. I was thinking a different amount came out with each filter but the level was the same before the oil change. My mistake.

What I now see is you have a car which you fill with a certain amount of oil and then 2700 miles later you have varying amounts left.

I would not first assume the filter but instead look for leakage or the car is burning some oil. Maybe harder driving or something simular. Lots of variables cause a engine to use oil.

Oil may look dirtier if same amount of contaminates are mixed in less amount of oil.

I can now see how you can have two quarts less one oil change compared to another.