FYI FORD MustangSteve's Ford Mustang Forum / Brake fluid choice

**Posted by RTM** 9/29/2024 11:14 AM

Since everything is new on my braking system is there a preferred goto brake fluid?

**Posted by Rufus68** 9/29/2024 11:32 AM

For a street car, if I were filling an all new Mustang brake system I'd choose DOT 4. It is compatible with DOT 3 and DOT 5.1 so there is that. And it has a higher boiling point than DOT 3 while being just as available as DOT 3. I would only change this choice if I had a specific reason for a specific car.

**Posted by Rudi** 9/29/2024 5:47 PM

After I completely redid my engine bay I put all new SS lines, front and rear calipers, disks, master cylinder and line lock .
I’m using DOT 5 all synthetic to prevent the regular brake fluid rot.
Ten years or more on, with one purge and refill I can report no issues.

**Posted by rpm** 9/30/2024 12:01 AM

After doing a bit of research I decided to go with LiquiMoli 5.1 fluid based on the boiling points and price.

**Posted by John Ha** 9/30/2024 6:38 AM

Just for information - there's a Dot 4 Plus fluid on the market (AKA "Heavy Duty Brake Fluid"). It has a higher boiling point (180°C versus 165°C) and lower viscosity than the Dot 4 fluid, and some say that it's supposed to be better at lasting if not flushed every 2 years. Mercedes (and, I think, some other manufacturers) recommends it in their vehicles.

**Posted by RTM** 9/30/2024 6:50 AM

I was hoping for a clear cut go with this fluid. Like everything there is always more than one option. Lol

**Posted by RTM** 9/30/2024 8:16 AM

rpm wrote:
After doing a bit of research I decided to go with LiquiMoli 5.1 fluid based on the boiling points and price.

Local Autozone has the synthetic DOT4 in stock in that brand. They also stock 5.1.

Last edited by RTM (9/30/2024 8:28 AM)

**Posted by KeithP** 9/30/2024 9:12 AM

Rudi wrote:
After I completely redid my engine bay I put all new SS lines, front and rear calipers, disks, master cylinder and line lock .
I’m using DOT 5 all synthetic to prevent the regular brake fluid rot.
Ten years or more on, with one purge and refill I can report no issues.

I am using DOT 5 too. Don't have a lot of time on my braking system yet, but so far so good. Brake pedal is firm and don't feel any difference so far from regular brake fluid. I used my pressurized master cylinder brake bleeding system to bleed the brakes by myself and check for leaks, no brake pedal pumping necessary.

**Posted by RTM** 9/30/2024 9:23 AM

KeithP wrote:
Rudi wrote:
After I completely redid my engine bay I put all new SS lines, front and rear calipers, disks, master cylinder and line lock .
I’m using DOT 5 all synthetic to prevent the regular brake fluid rot.
Ten years or more on, with one purge and refill I can report no issues.
I am using DOT 5 too. Don't have a lot of time on my braking system yet, but so far so good. Brake pedal is firm and don't feel any difference so far from regular brake fluid. I used my pressurized master cylinder brake bleeding system to bleed the brakes by myself and check for leaks, no brake pedal pumping necessary.

I may look into a power bleeder. Not sure my wife will want to pump the brake pedal with no seat in the mustang. Lol

**Posted by KeithP** 9/30/2024 9:30 AM

RTM wrote:
KeithP wrote:
Rudi wrote:
After I completely redid my engine bay I put all new SS lines, front and rear calipers, disks, master cylinder and line lock .
I’m using DOT 5 all synthetic to prevent the regular brake fluid rot.
Ten years or more on, with one purge and refill I can report no issues.
I am using DOT 5 too. Don't have a lot of time on my braking system yet, but so far so good. Brake pedal is firm and don't feel any difference so far from regular brake fluid. I used my pressurized master cylinder brake bleeding system to bleed the brakes by myself and check for leaks, no brake pedal pumping necessary.

I may look into a power bleeder. Not sure my wife will want to pump the brake pedal with no seat in the mustang. Lol

When I remade all my brake lines and connections I was able to keep the system pressurized for long periods of time to check for leaks. I had some stubborn leaks, so it helped me out a lot.

**Posted by RTM** 9/30/2024 1:25 PM

Never thought of keeping the system pressurized to check for leaks. That’s a great idea!!!

**Posted by rpm** 9/30/2024 3:04 PM

I have and love the Motive Products bleeder.

**Posted by Rudi** 9/30/2024 3:24 PM

I can’t recall how many cars I’ve bled brakes on with a small hand vacuum pump.

**Posted by RTM** 9/30/2024 5:45 PM

I don’t have a power bleeder yet but it has brake fluid.

**Posted by 6sally6** 9/30/2024 6:26 PM

I've always been sorta disappointed with all they new fangled doo-dad bleeders !
Invariably...I end up bleeding them with a human helper pumpin & holding the pedal.
Thankful brakes...for the most part...stay fixed once bled properly.
Type of fluid ?...Whatever's on sale ! (butt then...I've always lived on flat ground too ! )
6sally6

Last edited by 6sally6 (9/30/2024 6:28 PM)

**Posted by RTM** 10/01/2024 5:31 AM

I had the front left brake hose leak this morning. I didn’t tighten it enough, I actually forgot to check it. Lol