Why does Oil need to be changed 1 time per year?

[68redlines73]

I had a friend at work who NEVER changed the oil in her car. She just kept on adding a quart at a time relative to how fast it LEAKED out!

 

[Ray H]

quote:

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Originally posted by Schmoe:
Radiator fluid go bad? I know the BOOK says to change it but it's just water and glycol.

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Forget the corrosion and water pump bearing/seal wear inhibitors that are depleted over time?

 

[cryptokid]

mike, on the cap of the resivor on most cars, there is a pin sized vent hole. this is because when you press your brakes, fluid goes from the resivor and into the m/c to displace the fluid that was IN the m/c but for transfered to the brake lines.

so, in order to not create a small vacuum when the brakes are depressed, most resivor caps have a vent hole. my kia has one on the brake m/c as well as the clutch m/c.
my porsche has one, most vw's i have ever worked on have one, in fact most all cars have a vent hole. this lets air in the resivor when the brakes are depressed, and lets air out when you let off the brakes.

this means you get contaminated fluid quickly, well quick compared to your car i guess which does not have a vent hole.

 

[sprintman]

Change brake/clutch fluid annually. The fluid is hygroscopic and the water rusts wheel/master cylinders over time if not changed.

 

[cryptokid]

adding to sprintmans post, water contaminated brake fluid has the possibility of boiling under conditions in which you use your brakes alot.

or your clutch if it is hydraulic.

 

[dickwells]

The air pressure equalization in the master cylinder is the reason that they all (at least the ones I own) have a rubber diaphragm under the cap so the air can equalize but the fluid is still protected from moisture, etc.