Any of you guys running DOT 4 instead of DOT 3? I know they are comparable and interchangeable, and the 4 is a superior fluid, but I haven't talked to anyone who's actually swapped over.

 

I don't recall seeing just a 'DOT 4' version, but I've been using the Valvoline Synthetic "DOT 3 & 4" brake fluid for several years now and have not found there to be any braking issues or failures of any brake related parts..

I flushed out the whole system, using just about a full bottle of the stuff. Ran each corner until the fluid coming out was clear....

I noticed right away a much firmer brake pedal. I've since done another fluid swap, but it was harder to tell when the fluid got clear, as the 'old' Valvoline fluid was not really that dark.. The fluid is still pretty 'clear' in the master cylinder now...

Just my experience with it..

Mitch

 

It won't make a huge difference. Mitch probably just needed to bleed his brakes which is why he saw a difference.

The one thing that could matter - if you tow a lot, the DOT 4 will have a higher boiling point so you don't need to worry as much about boiling the brake fluid. I can see from his signature that Mitch tows a camper, so it is worthwhile for him to change to DOT4.

Just be sure that the fluid is a Glycol fluid. DOT5 fluid is Silicone based, and I have heard that some DOT4 fluids are silicone based. Your brake system may not be compatible with silicone fluids.
(DOT3 fluids are all Glycol based)

 

Hey Matthew,

I had originally bleed the brakes when I first got the truck (I didn't mention that before). The fluid was very dark. That initial bleeding didn't make any difference, then I heard that you should be flushing your brake fluid on a periodic basis, so I figured what the heck... That's when I noticed the firmer pedal. See, when I bought the truck, it had 65,000 miles on it, so I was doing all the maintenance on it from the schedule that should have been done at the 60,000 mile mark and then some!

6 years of towing with the current rig and another 6-7 years before that of towing various rigs of all shapes and sizes with and without trailer brakes and no brake related issues while towing, although I do what 'brake fade' feels like from those very early years!!

My trailer only weighs #5000 and I keep the brakes adjusted on it yearly. I have a Prodigy BC and that is the best thing ever!

I do agree that if you don't know what you are doing while towing, most people will boil their fluid real fast... I've followed several folks over the years and see that their brake lights are on for a good portion of the downhill run.... Even if you are not putting much pressure on the brake, but are 'riding' it, it will still heat up fast! I will run a lower gear if needed as well as apply the brakes hard to slow down a good amount and then let off. This slows you down, but when you let off, it gives the brakes a little time to 'cool' down between applications... I know I've smelt burnt brakes from the guy in front of me while they were just 'riding' the brakes and some of them weren't towing anything!

yeah, now that you mention DOT 5, that's the one I now recall as being the one you don't want to run in our trucks..... Well, at least the 'older' ones...

Good info Matthew and glad you called me on my post so I could explain a bit more of what I do!

Mitch