I have a ‘92 Ultra that I just re-wired and re-cabled and now need to fill the brake fluid...what DOT do I need to use? 2-3-4-5

The standard fluid for that bike was DOT 5.

But you never know...someone may have changed to another grade in the intervening 26 or so years. Caution. Stick with what was last in there.

This is correct but if you have changed out ALL rubber components you can use anything you want really. If not, to be safe you can use DOT 5.1 because it can be mixed with DOT 4 or DOT 5.

Sorry Ken but Dot 5 AND DOT 5.1 are totally incompatible. TOTALLY!!!!!

OK I’ll take your word for it as I have never tried it but it’s not what I was told prior.

And please don’t yell at me. I’m sensitive… You might hurt my feeling.



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OK I always admit when I’m wrong. I started thinking about it and the conversation we were discussing when I was told what you can mix was DOT 3 and Dot 4 mixing with DOT 5.1.

That was a while ago so I misspoke. That’s why I always read instructions and labels before I do anything. I don’t even trust myself. Most of the time anyway.


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LOl sorry for shouting and no worries. When 5.1 first came on the scene it was a very common mistake to mix 'em as ''both are Fives, right?'' Many found out the hard way. I have even had cycle shops telling me they are the same stuff. They really are a fast-track to goo in the brake system when mixed.

Thanx for all the help! New bars new cables and wires, now the master cylinders piston is not pushing nor pulling fluids....on to the next fix!

With a bike that age I would say it's best to just rebuild the master cylinder and calipers anyway. Not a hard job really.

Get yourself a mighty vac. Makes bleeding brakes easy. Also like ken said,a rebuild might be in order. Also very easy.