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Camaro Research Group Discussion => Maintenance => Topic started by: Z10Mike on September 03, 2026, 04:57:16 PM

Title: DOT 5 Fluid in New Braking System
Post by: Z10Mike on September 03, 2026, 04:57:16 PM
Been doing a fair amount of research online re: DOT5 vs DOT3,4,5.1 brake fluid in classic vehicle brake systems.  I previously used DOT 5 in a 1960 Vette with stock brakes and hoses.  It was in there for 15 years without incident.  Now I am reading new accounts of brake hoses swelling from DOT5 use and causing problems. My intent was to avoid any issues during bleeding or maintenance that would attack my new body and undercarriage paint. Because nothing like that would ever happen...right?
Does anyone have actual experience with DOT 5 in your car?
Title: Re: DOT 5 Fluid in New Braking System
Post by: GMAD_Van Nuys on September 03, 2026, 05:35:59 PM
There was a recent discussion about the use of DOT 5 brake fluid on CRG:

https://www.camaros.org/forum/index.php?topic=21936.0

Title: Re: DOT 5 Fluid in New Braking System
Post by: David K on September 03, 2026, 06:52:15 PM
The silicone appears to be the culprit, DOT 3 or 5
Title: Re: DOT 5 Fluid in New Braking System
Post by: Z10Mike on September 04, 2026, 08:50:40 AM
GMAD - Thanks for the link for reference.  I missed that one.
Title: Re: DOT 5 Fluid in New Braking System
Post by: GMAD_Van Nuys on September 29, 2026, 04:12:45 PM
Motive has a cover that you can put over a dual reservoir master cylinder and avoid spilling brake fluid as you pressurized the brake system and bleed the calipers/wheel cylinders by opening the valve:

https://www.summitracing.com/parts/mvp-1105?seid=srese1&ppckw=pmax-tools&gad_source=1&gad_campaignid=19201424812#overview

I use a MiniVac hand-powered vacuum pump to empty the master cylinder and to bleed the brakes on my vintage cars and those that have ABS without a problem.
Title: Re: DOT 5 Fluid in New Braking System
Post by: x66 714 on September 29, 2026, 05:00:34 PM
Quote from: Z10Mike on September 03, 2026, 04:57:16 PMBeen doing a fair amount of research online re: DOT5 vs DOT3,4,5.1 brake fluid in classic vehicle brake systems.  I previously used DOT 5 in a 1960 Vette with stock brakes and hoses.  It was in there for 15 years without incident.  Now I am reading new accounts of brake hoses swelling from DOT5 use and causing problems. My intent was to avoid any issues during bleeding or maintenance that would attack my new body and undercarriage paint. Because nothing like that would ever happen...right?
Does anyone have actual experience with DOT 5 in your car?

Read post 2 & 3 from the thread link provided.....Joe
Title: Re: DOT 5 Fluid in New Braking System
Post by: x66 714 on September 29, 2026, 05:51:29 PM
I will add that this was in April of 2024 when I had to do all that work. I changed to DOT 4 & the problem no longer exists. Mike Gibbons also indicated that he will not warrantee any brake component that has been used with DOT 5 fluid.....Joe   
Title: Re: DOT 5 Fluid in New Braking System
Post by: Z10Mike on September 29, 2026, 07:59:23 PM
Thanks to all who replied with information and advice. I went with conventional DOT3 brake fluid.  Was sweating bullets until I got all the flares seated and avoided any drips on the paint. The worst connection was at the frame mounted valve to rear line fitting.  Took some work to get that one to stop weeping. 
Title: Re: DOT 5 Fluid in New Braking System
Post by: GMAD_Van Nuys on September 29, 2026, 08:47:55 PM
I only commented about the master cylinder cover being available as a way to prevent brake fluid (no matter what the type used) from spilling out into the engine compartment.  I even bought an OBD2 scanner that can reset the ABS unit if I got air into the system.  I will admit that working on brakes has never been much fun for me!
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