Engine Oil Standard Attributes

[aspearin1]

I am looking for standards (ASTM) or other that are generally accepted as measurements to determine oil quality. (i.e. how is it determined that my oil needs to be changed or not?) What attributes are most important? (Density, viscosity, suspended solids?) I've read about these nifty systems used by corporate fleets which have shown capability to extend the life of the oil 3-4X... I'm curious about the test criteria. Thanks in advance.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[25362]

There are several Google sites discussing the subject of extended engine oil-change intervals.

As for examination of used oils, these are some of the ASTM tests generally applied when comparing them to newly formulated lubes, beside density, viscosity, VI, pour and cloud points, flash and fire points:

D3524: Diesel fuel...
D322/IP23: Gasoline dilution...
D3525: Fuel dilution in gasoline engine oils...
95/IP74: Water...
D893: Insolubles...
D4055: Pentane insolubles...
D874/IP163: Sulfated ash ...
D2896/IP276: Base number...
D4739: Base number...(alternative)

As for their significance, all physical, chemical, laboratory bench tests and engine tests are extremely valuable tools to predict how a lube, new or used, will perform. But they are not infallible or foolproof.

Ultimately, the oil's behaviour in the particular engine, or equipment, will dictate whether the oil is suitable for the purpose or not. "Recommendations" by car manufacturers on a specific brand name are common. Major oil suppliers sometimes provide warranties on the extended intervals between changes of their make.

 

[Xtrema]

It would be difficult to set up a test program in house for the tests referenced above. There are outside test houses that can perform "Used Oil Analysis." Many of these are allied with suppliers of high-zoot engine oil like Amsoil.

http://www.bobistheoilguy.com

is a site frequented by both oil aficiandos and you may find more information there as far as maintenance extension and outside UOA. I cannot state that everyone there is an expert.