New Synth Brake Fluids

[Laney]

They seem to have taken over all the shelf space in my area, the only non-synthetic I could find was the house brand at Walmart, and then only in DOT 3.

 

I ended up buying a bottle of Vavoline Synthetic Formula, described on the label as "exceeding DOT 3 & 4", and "compatible with conventional brake fluids".

 

It doesn't sound like there's a problem mixing this with the old stuff in the bike, but before I take the cap off and add some to he reservoir on the RS - does anyone know anything otherwise? If there's a known problem with mixing the two, where do I go to find the "vintage" non-synthetic stuff?

 

If course, there's still the question of why my RS loses brake fluid since it was flushed last year - I'm still open to any suggestions of what to check...

[Firefight911]

I'll let other, more technical engineering (read, propllor heads ) types chime on the fluid type.

 

As for the fluid loss, is it a loss of fluid or the fact that as your pads wear, the caliper pistons move out, thereby reducing the perceived fluid level?

[Laney]

As for the fluid loss, is it a loss of fluid or the fact that as your pads wear, the caliper pistons move out, thereby reducing the perceived fluid level?

I’m not sure, I only know that I’d never had any unusual or significant brake fluid loss from the time I got the bike (July ’03) until Irv Seavers BMW did the fluid flush in Dec. of ’05.

 

After that, brake fluid started disappearing from the rear reservoir at a fast pace, but never showed up anywhere. Taking everything removable off the bike, washing it with Simple Green and toothbrushes never showed where the fluid goes to, comes from, or whatever. Parking the bike with sheets of white paper underneath never showed anything either.

 

It just simply disappears… Periodically I get the ABS fault lights on because the fluid’s too low, and I start wondering where it’s gone. It seemed to level off in the warmer months, but now that it’s cold again, the “Continuous Brake Fluid Change Feature” is back.

 

The next fluid flush will be done by Caring Non-Professionals - that'll probably make everything work the way it's supposed to!

[99Roadster]

The Valvoline stuff should be fine to use. Exactly the same fluid I use when flushing since that's all that is available here as well. It is DOT 3 and 4 compatible.

 

As far as the fluid loss - have you checked all the connections - reservoir, ABS bleeders, banjo bolts (mine has loosened in the past), bleeders. It doesn't just evaporate

[awagnon]

I'm not sure where you are indicating the fluid level goes down. I thought if you had ABS2 or ABSN brakes, the control circuit fluid level only went down due to a leak. The control circuit fluid is different from the brake fluid to the brake calipers. The later fluid does go down with brake pad wear, but you would only know it when you get a brake fault warning since the fluid reservoir is in the control unit.

[Laney]

The rear reservoir is the one that loses fluid -

(photo from i-bmw.com)