in 40 + years of driving, I've never changed brake fluid unless I was servicing the brakes and needed to bleed them afterwards. I understand preventive maintenance but I'm also a guy who doesn't bother to wash my modern cars more than once a year.  The classics get the wash and wax.

2 to 3 years.  That's pretty much recommended regardless of the fluid type or ambient humidity.

Thanks - all good info here.

Follow-up question. How often should Dot4 fluid be replaced on a time base in a Mini. I was doing it every 3 years in Seattle, figuring every 7 years here in Colorado is good (VERY low humidity).

Personal experience.

Willie followed me from the host hotel to a Walmart at MMEMW in 2004 and reported that the brake lights on Paul Strieby's S weren't working.  They were, it just took far more pedal pressure than I was using to activate them.  If you're aiming for a 100pt resto and don't want to fit an electric switch, don't use silicone.

The pedal on Gertie is the best in the field, and that's on Dot 4 compared to the 5 or 5.1 that most of the others are using.  you can feel the sponge in it.

I used to be a fan/convert to the church of silicone fluid. 

I no longer use it, mostly for the reasons mentioned. Keep in mind I daily drove for decades. S discs or larger and DOT 3 serviced regularly are what I do now.

Hmmm.  Mixed endorsements.

Anyone had an actual brake failure or the brake lights not lighting up with DOT 5?  Silicone?

Alex - is that your personal experience?
Thanks.

I also don't care for it and don't use it unless the customer requests it. It seems there are some brake rebuild kits that don't like it either. I have been using DOT 3/4 for maybe 55 years. We all know you can't put it on painted surfaces. It should be flushed every couple of years. If you have ever had mechanical brakes the issues with common brake fluid are no big deal. Steve (CTR) 

Don't like it, don't use it.  It is incompatible with our hydraulic brake light switches due to compressability, the same compressability that leads to a crappy pedal compared to DOT4.

Great idea! I'll use it next time.

cause the parts guys sometimes never worked on a car and they rely on looking everything up in their computer data base.

I also got the same question, what car is it for? The parts guys do not want to help with a "silly foreign car". I would always tell them it was for a "custom hot rod". They would usually, go out of there way to help out.

There are a lot of nay-sayers about DOT-5.  I don't listen to them.  I have DOT-5 in the Mini, the GT6, and had it in the Spitfire. 

My advice is as follows (some of which won't apply to you since you have new parts).
Replace all system rubber including all seals, flex hoses, PDWA seals, and bias valve.
Use the metal over-braid flex hoses during the system rebuild.
Flush the metal lines with isopropyl alcohol (several times allowing a soak period for each) then blow dry with compressed air.
Do not shake the DOT-5 fluid.
When filling reservoir, take a clean screwdriver, place its tip in the bottom of the reservoir and pour the fluid down the shank.  This prevents bubbles.

This always drive me crazy. I'll go in to an auto parts store and ask for something as generic as a valve stem cap and the counter guy will ask me what car it's for. I'll tell him 2 or 3 times that it doesn't matter. Eventually he'll wear me down and I'll tell him it's for a 70's classic Mini. Next he'll spend 5 minutes noodling around on his computer before telling me they don't have any one. Sheesh. 

Thanks.  I know DOT 3 is hydroscopic, absorbing water through the cast iron calipers and atmosphere.  Any know the total capacities of
both an S brake set up and std. clutch  in total. 

I bought a quart which I'm pretty sure is sufficient  including a bleed.

I only second guessed my self, because the auto parts salesman started asking me constantly what car it's for.  It through me off and I thought maybe I should ask you all.

Mike,
We have been using DOT 5 Fully silicone Brake fluid in all our street Minis since  1987.
When bleeding the system in to a clear jar you will see that the regular dot 4 will not blend with the dot 5 .
So you can blow out the system or simply use the DOT 5 to purge the old stuff..
It may be more expensive but it will save  you a ton of money in the long run..
Deb

The only drawback is Silicone is more expensive than DOT 3 or 4. IMO it's the only way to go. It's in my daily driver mini. There are making silicone in DOT 4. Haven't tried it yet but I have a quart.

If your not going to drive it lot's, water will build up in the brake lines which will rot out the pipes and possibly cause freeze damage, brake fluid will absorb moisture from the air, silicone will not, it just pools in droplets in the system.

I've got new brake and clutch components, never had fluid in them.

Any reason I should not use silicone?

1960 mini, built to S specs with A series lump, pre verto clutch slave.