Brake Fluid Flush

[Diesel85]

I want to do a brake fluid swap because my fluid is in a yellow condition on my tester.

I also need to order a couple things from Geno's, and I saw some Motul DOT 5.1 brake fluid.

Anyone have any comments on the Motul fluid?

https://www.genosgarage.com/product/ap-dot-51/brake-fluid

 

[Ozymandias]

I'd recommend to use what was factory fill.

Fun fact about brake fluid - the higher the number the higher the boiling point. So far so well known. But also - the higher the number the faster it ages and needs replacement.

I went back to DOT.3 after two years with 5.1

 

[Diesel85]

Thanks for the input and advice. What do you recommend for DOT3 brake fluid?

 

[Ozymandias]

I used Lucas #10826 because of the price and it was easy available.
It needs about two quarts to properly flush the system.

 

[Diesel85]

Thanks for the information. I appreciate the input.

 

[BigPapa]

What year truck do you have?

 

[Diesel85]

It's a 2020 EcoD 1500.

 

[BigPapa]

Gotcha. I was just checking to see if they'd moved to DOT4.

 

[Diesel85]

Gotcha. I was just checking to see if they'd moved to DOT4.

Nope. Still DOT 3, even on current 2023 models.

I don't expect them to switch anytime soon. If they do, possibly DOT 4 might be the highest. DOT 5.1 is for extreme severe duty applications or folks that just want that piece of mind I guess.

After researching and what folks said on here, the biggest difference for us folks who drive trucks is the longevity of the fluid in terms of the rate at which it absorbs water. DOT 3 a much slower than say DOT 5.1. However, it's a moot point if you flush the brake fluid 2-3 years.

My fluid looks OK in the reservoir (possibly a slight hint of yellow, but hard to tell), but my little gadget gave me the yellow warning light to recommend changing it.

Ever since a limo accident that killed 20+ people in my neck of the woods and made US headlines, I've been kind of anal on my brakes on all my vehicles.

 

[BigPapa]

DOT3 & DOT4 contain Glycol which attracts water. The difference between DOT3 and DOT4 is the boiling point. DOT3 is 401*F dry, DOT4 is 446*F dry. They can be mixed without problems. DOT5 is silicone based and must never be mixed or used in a system that has had 3 or 4 in it without a complete clean and flush. DOT5 is very popular in motorcycles due to it's higher boiling point, 500*F dry. The reason you don't want water in your system is that it drastically reduces the boiling point and, when it boils, it increases pressure and compressibility in the system.

Motul (and possibly others) offers two synthetic DOT4 fluids that have a higher boiling point, RBF 600 (594*F dry) & RBF 700 (637*F dry).

You can see the specs on them here:

https://www.motul.com/us/en-US/products?facets[application]=144&facets[range=25[/URL]

 

[Diesel85]

DOT3 & DOT4 contain Glycol which attracts water. The difference between DOT3 and DOT4 is the boiling point. DOT3 is 401*F dry, DOT4 is 446*F dry. They can be mixed without problems. DOT5.1 is silicone based and must never be mixed or used in a system that has had 3 or 4 in it without a complete clean and flush. DOT5.1 is very popular in motorcycles due to it's higher boiling point, 500*F dry. The reason you don't want water in your system is that it drastically reduces the boiling point and, when it boils, it increases pressure and compressibility in the system.

Motul (and possibly others) offers two synthetic DOT4 fluids that have a higher boiling point, RBF 600 (594*F dry) & RBF 700 (637*F dry).

You can see the specs on them here:

https://www.motul.com/us/en-US/products?facets[application]=144&facets[range=25[/URL]

DOT 5 is silicone. My motorcycle takes it and it's totally different.

DOT 5.1 is traditional Glycol like DOT 3 and DOT 4, but with a higher boiling point.

 

[BigPapa]

DOT 5 is silicone. My motorcycle takes it and it's totally different.

DOT 5.1 is traditional Glycol like DOT 3 and DOT 4, but with a higher boiling point.

Thank you. Yes, you are correct. My apologies for the improper use of the ".1". I will edit my post to correct it.

 

[Diesel85]

Thank you. Yes, you are correct. My apologies for the improper use of the ".1". I will edit my post to correct it.

No worries here!

Thanks for the input. It's appreciated.

 

[User113]

Can't decide between DOT3 and DOT4? Go for one that has both ratings, DOT 3&4.

Valvoline

Motul

Peak

Amsoil

Johnson's

 

[Diesel85]

So I had some spare time today and swapped the fluid. I also took each caliper off, cleaned them up and refreshed the lube on the slide pins. I am totally glad I did. I actually notice a slight performance increase in my brakes!

I used my vacuum bleeder and as usual, it makes quick work of this type of stuff.

I did decide to go with the Motul DOT 5.1 fluid just to see what if it really is good. Probably overkill, but whatever, it was a few bucks more than local synthetic DOT 3. I used up 3 bottles, had a little left over to show what new fluid looks like.

From now on, every 2 years max on brake fluid!

Here's what came out at a little over 3 years and 52,000 miles: