What Function of Oil Wears Out First?

[amateurbob]

Things are only as strong as their weakest links. What function in motor oil usually wears out first?
I am not well versed in reading used oil analysis or understanding the all the components of motor oil. Is it oxidative capacity, the seal softeners, heat dispersion etc?

 

[4wd]

How long is a rope?

 

[AZjeff]

That's a good question. Waiting for guesses...er... answers.

 

[BMWTurboDzl]

Things are only as strong as their weakest links. What function in motor oil usually wears out first?
I am not well versed in reading used oil analysis or understanding the all the components of motor oil. Is it oxidative capacity, the seal softeners, heat dispersion etc?

Probably the additive package

 

[fantastic]

Things are only as strong as their weakest links. What function in motor oil usually wears out first?
I am not well versed in reading used oil analysis or understanding the all the components of motor oil. Is it oxidative capacity, the seal softeners, heat dispersion etc?

If you're using the right oil for your application it could be viscosity loss or oxidation. However, That really depends on the oil & engine it's in what goes first. There isn't a single answer in every situation as it may be fuel dilution that ruins the oil or high Si reading that requires the oil to be dumped. If viscosity is still showing a reasonable number, then oxidation would be next barring any high metal contamination.