Dot 5.1 Brake Fluid Change

[feb 47]

Does this have a shorter lifespan than the DOT4 one that most manufacturers use?

I have done 16-17k miles in 12 months with the DOT5.1 fluid and the car has been used daily (i.e. not abused) apart from 20-25 laps at the Ring.

Should I change them or can I keep them longer?

Various specialists state they should be changed every 2-2.5 years (20-30k miles) but I suspect this applies to DOT 4 fluid and I am wondering whether the same applies for DOT5.1 one.

Cheers!

Edited June 8, 2011 by feb

[Anthony 1,002]

Depends what you're going to be doing IMO.

 

For road use, 2-3 years would be fine.

 

For track use, especially in a heavy bruiser of a car like a Forester, you'll probably be wanting to flush it through every 12 months or so maximum.

 

Remember that brake fluid doesn't go from as-new to needing replacement instantly, but slowly absorbs water and the boiling point gradually reduces as time goes on. For road use, that lowering boiling point probably isn't such an issue, but on track where you'll be putting alot more heat through the brakes it is.

[philfingers 5]

i change it every two years, the issue is the water absorption, it causes rust spots in calipers and m/c's which cause a whole load more work than 1/2 hr to bleed it!

[feb 47]

Thanks guys, I will change them sooner rather than later then. Not really planned any trackdays this year, maybe 1 if at all but will be going down to Stelvio hopefully this weekend; I will have to take it steady on the descend if I don't manage to change them before that.