Dot3 or Dot4

[yody]

I have a 100% brand new braking system, everything is new, should i fill it up with dot3 or dot4? what are the pros and cons?

[Travis B]

we use all DOT5 because if you spill it won't eat paint.....
Just an idea for you!

[MuscleRodz]

I know DOT 3 makes a dandy paint stripper. I would use a silicon brake fluid. Won't eat paint.

Mike

[deadcarny]

hmmmm... where do you get the 5?

[Travis B]

hmmmm... where do you get the 5?

Now you have me wondering

I am pretty sure it is 5 I will check tonight!

[CarlC]

If you plan on using the car for track days you may want to re-think using the silicone fluids. Check the archives, there's some not-to-good stories.

The NAPA fluid is great. It used to be sold under the Heavy Duty label and may still be found, but the newer version is their Premium brand, DOT 4, both with a wet boiling point of 311*F. This is the same fluid as the HD Ford type.

[rockdogz]

I am by no means an expert on this, but the research I did said to use synthetic fluid but not silicone fluid. I'm pretty sure DOT 5 is all silicone, so I went with DOT4 synthetic...

[deadcarny]

oh, NM then about the 5...

[wick]

Have any of you heard of Motul? They make alot of products for bikes and they are very good. I raced motorcycles off road for many years and would boil the fluid in the rear especially in long two hour muddy race. Once I switched to Motul I it only boiled once.

[MuscleRodz]

I am by no means an expert on this, but the research I did said to use synthetic fluid but not silicone fluid. I'm pretty sure DOT 5 is all silicone, so I went with DOT4 synthetic...

Synthetic is what I meant, not sillycone!

Mike

[rockdogz]

Mike,
I think you were right the first time though - silicone won't damage paint, but I believe synthetic still will. Silicone (DOT 5) however will give you a mushier pedal though. (is that a word?)

[yody]

So carl, do i want the new premium version, or the old version?

[68BNUT]

Whats the heat rating on that DOT 5 fluid??

[rockdogz]

500 degrees F

[CarlC]

So carl, do i want the new premium version, or the old version?

I believe they are the same fluid.

NAPA has a so-called "new" DOT 3 Heavy Duty fluid that has a 284* wet boiling point fluid. This is the less expensive fluid that has in big red letter "450 boiling point" on the front of the label. It also says "Heavy Duty". But it is not the better DOT 4 fluid.

The older labeled DOT 4 Heavy Duty fluid and the new labled DOT 4 Premium fluid, I believe, are the same. Check the label, they will both have a 311*F wet boiling point. I just went through all of this on Saturday while buying fluid to flush out the "old" DOT 4 Heavy Duty fluid.

The main reason that I like the NAPA fluid is that it is inexpensive, it works very well, and can be purchased in every small town in North America. I had to replace the caliper dust boots on the PBR calipers because they melted, but the fluid did not boil.

[yody]

okay, hopefully the brakes will bleed with no probs tomorrow. So close to driving it!! out of curiousity, why does the not so good stuff does it say in big red letters; 450 boiling point if it is only 284?

[CarlC]

Dry vs. wet boiling points.

[yody]

is all dot4 synthetic?

[MarkM66]

I've seen even the el cheapo DOT 3 says synthetic on it now. I think all brake fluid can technically be called synthetic.

[jy211]

we use all DOT5 because if you spill it won't eat paint.....
Just an idea for you!

I use DOT 5 in my chopper....I'd go with that!