Mark Leger

Has anyone had any issues using motul and it causing the seals to fail on the brake master cylinder? I have noticed that I've been replacing the brake master cylinder when my pedal feels mushy and it fixes it. After a couple months of motul in the system the same issue comes back. I replace the brake master cylinder and then the problem is fixed again. Has anyone seen this problem and if so have you tried a different brake fluid that maybe isn't so hard on the brake seals?

VanSpeed

I use Motul RBF 600 in my 2008 Z06 without any issues. I flush before a track day then leave it in for all other driving, road trips, just fun drives. I’ll leave in for many months over the winter as well. No issues here.
Brian

Z.06

I also run Motul 600 brake fluid in my gently modified 2008 Z06, and I am totally satisfied with it. I change it out every 6 months. I do run my car on a road course which tests the brakes by slowing the car from 120 mph to 45mph in a corner. No issues, no seal failures using OEM brake calipers and XP10/XP8 pads on DBA disks. Hope this helps. My brake master cylinder was replaced once by GM under warranty, but I have not seen any change in the braking as a result. I will keep using Motul 600. Hope this helps.

Mark Leger

My car is track only heavily modified and ran very hard on track.

Hib Halverson

Hard for me to imagine that Motul 600 is causing the problem. Have you disassembled one of the "failed" masters to see if the seals inside have actually failed?

Have you switched brake fluids, say to Red Line RL600, to see if a fluid change has any effect?

When you change masters, are you bench-bleeding them before installaiton?
How to you bleed the base brake system, by foot or pressure bleeder?
Do you run the ABS autobleed procedure with a scan tester ever time you open up the system?

Mark Leger

I have ran auto bleeds, bench bled new master cylinder and seals I didn't check. haven't tried different fluid but plan to this time around when I throw in another master cylinder.

Pb82 Ronin

Easy problem to check. Switch fluid if it doesn't work for you. If the problem still persists, it's not the fluid. Amsoil Dominator, RL600, Castrol...all good choices.

jayyyw

Have you tried bleeding the brakes when that symptom arises?

Keppler

This.

I have had Motul 600 in my C6Z HPDE track car for the past 4 years with no issues. However I do partially bleed the brakes after every track day.

At 12 hours of track time I do a full bleed.

I am running AP Racing brakes.

At high speeds the brakes must not fail.