Fluid Changes

[hursst]

Hello,

   With many of our old cars, we don't put enough miles on them to facilitate fluid changes based on use, but it ends up being based on time.  How often (in years) do folks change out their rear axle fluid, manual transmission fluid, and brake fluid, when the cars are not driven enough to hit mileage requirements?  I am wondering if I may be going too long, or changing too short.  Thanks.  

 

Chris

[JFranklin]

I don't worry much with trans. and rear axle as the lube does not deteriorate over time, only mileage. Brake fluid if not DOT 5 should be flushed over time but I don't worry much with DOT 5.

Edited November 10, 2019 by JFranklin
Spelling error (see edit history)

[edinmass]

Certain oils can become acidic over time. Every ten years is fine. Be sure to run the car hard at speed for an hour before draining the oil. Overnight draining is best.

[JFranklin]

3 hours ago, edinmass said:

Certain oils can become acidic over time. Every ten years is fine. Be sure to run the car hard at speed for an hour before draining the oil. Overnight draining is best.

Engine oils and some antifreeze become acid due to chemistry of combustion but I doubt gear oil does. 

Edited November 10, 2019 by JFranklin (see edit history)

[hursst]

Thanks for the tips.  I think I'm probably okay with my gear oil, then.  I'm up to 14 years in my more modern car, but it's only been 9,000 miles since then, plus I'm using synthetic.

[edinmass]

Its the old early oil that was acidic, many cars have transmission oil from the 40’s and 50’s in them still. I could show you a dozen transmissions that were pitted and the gears damaged deeper than the heat treatment on the teeth. Probably 90 percent of the cars have very oil oil in the transmissions, rear ends, and shocks. 

[JFranklin]

When I buy an old car I replace all the fluids because you never know what was used, and how old it is.