Lifespan of fluids

[Jacob Dryer]

Why is oil so short when compared to rear diff fluid or transmission fluid? Is it because of so much heat or is there some other factor?

 

[Tom Schindler]

Trannys will get very hot too.



The main factor is gasoline in your oil. Yes, there can be gasoline in your oil.



On start-up, your pistons are not completely sealed witin the cylinder walls. You get blow-by, and normal compression loss, past your piston rings. Your oil get contamininated by those gasses. It will produce acids.



The tranny does not create that dirt in the system, neither does the differential.





Tom

 

[Todd Z]

The rear is also 80w90 or 140 weight oil, a lot thicker......... can Handel longer higher temps and such.



An engine has too many tight clearances to run that thick of an oil...



Edit: Don't forget the moisture created in the engine as well by combustion and the temperature fluctuation...



Todd Z

 

[Tom Schindler]

Actually Todd, there was 80w90 for the open differentials and 75w140 synthetic for the Limited Slip differentials.



I also forgot to comment on the moisture. Thanks for bringing that up.





Tom