I need to see if anybody can help me. I am switching to DOT 5 Fluid, and I read on the back of the bottle, that it is not compatable with DOT3, and to flush the system with DOT 5 first. How serious is this, to I need to flush it more than once? Also, has anybody switched to DOT 5 and ave you noticed a difference?

Ron Smith

 

DOT 5 is silicone-based, and is "bad ju-ju" for cars designed for DOT 3 or 4. However, the new DOT 5.1 spec is compatible with DOT 3/4.

Why are you switching? If it's for higher boiling points, then there are plenty of DOT 3/4/5.1 fluids available that should meet your needs (try a search).

 

Yeah, stay away from DOT 5. If I remember correctly, its made for race cars and motorcycles. Could be wrong though.

I don't know anything about the DOT 5.1 though.

 

I already bought the DOT 5 fluids. I want to switch because I am an avid beleiver in using the best fluids out there.

Ron Smith

 

Going back to what twohoos mentioned, DOT 3/4/5/5.1 is merely a spec. Newer specs do not mean better. They could release a DOT 6, and it might not be any better, just a slightly different spec for a different application.

I was told never to use DOT 5, but I don't know if it'll actually do damage if you use it.

Blake

 

Ron, get a bottle of Motul RBF 600 if you are going to be tracking the car. Otherwise go with the ATE Super Blue racing fluid (cheaper and you get more). Some people use ATE on the track. I switch back and forth.

 

By what standard do you choose the "best fluids"? Do you use 80W-140 in your engine, just because it has higher numbers than 10W-30? I hope not.

 

I do not know much about brake fluid, I thought it might just have a higher temp rating, which apparently it does, in which case, it would be similar to using higher octane gas. For the record I use 5 or 10 weight 30 synthetic.

Ron Smith

 

You have to consider the wet boiling point and dry boiling point. Some fluids are more hygroscopic making them slightly higher maintenance. Example-Castrol SRF. Expensive and very sensitive to water. I know people that swear by it. Have you experienced brake fade to any degree? Are you boiling over fluid? What brake pads are you using? The more aggressive the pad, the higher heat the fluid has to sustain. It might help if you could disclose you driving application.

 

Dont use the DOT 5 fluid. Take it back to the store and exchange it for a good DOT4 fluid. Valvoline or castrol synthetic DOT4 would be great.

Do some searching and research here before you try use the DOT 5 fluid if your determined to do so. It'll save you a lot of expense.