The DOT 5 brake fluid conundrum.
Race Director
Joined: Mar 2017
Posts: 11,797
Likes: 4,420
From: Virginia
O-rings are pretty cheap. Perhaps buy a few of the correct size, and repeat your experiment.
As @4-vettes suggested, Viton would be my suggestion, if I had to run DOT 5. Grok suggests EPDM, and sources a Corvette Forum posting. Even better, I'd suggest you carefully consider NOT using DOT 5.
https://www.corvetteforum.com/forums...id-please.html
As @4-vettes suggested, Viton would be my suggestion, if I had to run DOT 5. Grok suggests EPDM, and sources a Corvette Forum posting. Even better, I'd suggest you carefully consider NOT using DOT 5.
https://www.corvetteforum.com/forums...id-please.html
Racer
Joined: May 2020
Posts: 497
Likes: 167
I was experiencing fade when doing some “spirited” driving so I purchased a DOT 5.1 brake fluid. It is glycol based unlike DOT 5, but has a higher boiling point than DOT 4. I haven’t put it yet, because bleeding all the fluid out of the brakes will be a pain.
Last edited by JC 1975; Apr 11, 2026 at 02:45 PM.
Drifting
Joined: Jun 2025
Posts: 1,568
Likes: 553
Do suggest a flush, BUT DOT 5.1 (NOT simply 5) is completely compatible And miscible with either DOT 3 Or DOT 4.
3rd Gear
Joined: Apr 2026
Posts: 3
Likes: 1
O-rings are pretty cheap. Perhaps buy a few of the correct size, and repeat your experiment.
As @4-vettes suggested, Viton would be my suggestion, if I had to run DOT 5. Grok suggests EPDM, and sources a Corvette Forum posting. Even better, I'd suggest you carefully consider NOT using DOT 5.
https://www.corvetteforum.com/forums...id-please.html
As @4-vettes suggested, Viton would be my suggestion, if I had to run DOT 5. Grok suggests EPDM, and sources a Corvette Forum posting. Even better, I'd suggest you carefully consider NOT using DOT 5.
https://www.corvetteforum.com/forums...id-please.html
I've been using DOT5 for close to 40 years and the only scenario I would 100% agree to not use it is for high altitudes. Back in the 80's I drove up the Mt Washington auto road and when I got to the top, the brake pedal went to the floor and had to be towed down the mountain. Once I got to the bottom the brakes were back to normal.
Something else I've learned from this is that the silicone in DOT5 does not react with EDPM the same way silicone lubricant does. One seems to shrink o-rings and the other makes them swell.
I'll be back in a few weeks with Viton findings
Last edited by sg66; Apr 13, 2026 at 10:51 AM.
