Sev

Hi guys, what the heck is the difference between DOT 4 and DOT 5 brake fluid... Never been into brake mods until now.

I just bought some DOT 5.1 motul brake fluid for my CRX, I still don't know what the heck this all means.



Thanks for your help.

XTC at 9K

i much much of a brake guy myself....but the "DOT"'s are somewhat of a rating system. the higher the number the higher the boiling point of the brake fluid, for racing situations etc. DOT 3 is what Honda Brake fluid is. I know that you can mix DOT 3 and DOT 4 brake fluid. But i believe DOT 5 is made up of a silicone base and SHOULD NOT BE MIXED WITH ANY OTHER TYPE OF BRAKE FLUID WHAT-SO-EVER!! Hope this helps??

cdelena

Unfortunately DOT sucks at assigning designations. The DOT 5 is silicone and not compatible with other fluids, but DOT 5.1 is the latest synthetic which is compatible with DOT 3 & 4. Some vendors sell it as Improved DOT 4 just to avoid this confusion.

coop

I dont know about Dot 5.1, but Dot 5 if used on an old system could leak. Dot 5 does not treat the seals like Dot3 or 4.

Sev

So Dot 5.1 should be good in an old 1989 CRX then????????

cdelena

Will work great.. it is the best choice for a car that is driven.

Sev

Thanks. I appreciate your help.

Same goes for everyone. Thank you.

CoralDoc

Chris - Are you still using Valvoline Synpower (DOT 3 & 4)? I've not noticed DOT 5.1 fluid at the local Discount Auto parts - is it only sold at specialty stores?

BTW, the stiffer Comptech front bar is the best thing that I've done to the car - I can now understand why there are so many people that raved about the Mugen bar.

cdelena

No, the Synpower stuff worked ok (still used in the wife's car), but I found a deal on the Neo fluid, and I buy Motul when I get pads since Carbotech discounts it with a purchase. Both have higher dry boiling point so maybe I can skip the end of track day bleed often needed.

Yes, I think the larger front bar is an improvement but there have been some that do not like it.