Can anyone tell me why motor oil gets thicker after use? (by that i mean.. the increase in viscosity of used oil analysis vs brand new oil) could it be due to all the "deposit" trapped in use motor oil?

 

I thought Oil should thin out as it got contaminated with water and fuel...Unless your engine is very dirty and sludged up or something...

 

Oil is a misture of hydrocarbons of various chain lengths. Every time you heat it up the lighter (shorter) fractions are more likely to evaporate off, leaving the thicker/longer chains behind.

This is similar to the fractional distillation they use to turn crude oil in to various petroleum products. Each product (gasoline, kerosine, etc.) boils off at a different tempreature. The various names just refer to different fractions that come out of the mixture.

Oil can get thinner if gasoline mixes into it. But that is unlikely to occur in a car motor since the heat would evaporate the gasoline back out of the oil pretty quickly. (and in to the PCV valve and back in to the motor).

 

ditto, i think it gets thinner.

 

If you leave motor oil in your car, never change it and just keep add new oil when low. You will cook the oil from the increasing friction, and oil slug will begin to deposit on the top of the heads and other places.
Maybe this is N8vz question

 

Did you know that Kerosine was once a brand name like Xerox and Coke? We misused it into a general product type. I want a coke. What kind? Uh, 7Up. Can you Xerox these papers for me over on the canon copier?

 

will someone please get me a KLEENEX to wipe this oil off my hands. How about that one?

 

How true, how true.

 

I think they're next to the Band-Aids and Dixie Cups.

 

Quit it guys, you're giving me a headache. Now I need an ASPIRIN.