From memory, my 2004 FXSTS used DOT 5. My 2007 FXSTC uses DOT 4. I guess Harley switched back. (????) I had to thank the guy at the parts counter because I was about to buy DOT 5 for the 07 when he told me it uses DOT 4. I asked why they switched "back" and he shrugged his shoulders.

By the way, I did accidently mix in the front master cylinder and then simply flushed a feew times with the DOT 4 and now use DOT 4. No rebuild required, BUT I only had itr in there for a few minutes when I realized my mistake.

 

I like the test... Best way to be sure... Take a couple of drops of the existing fluid into a cap full of the dot 5 or dot 4... If they blend you are good to go. If they separate, then keep looking.

 

I have an 04 Deuce that I bought a Harley multifit chrome Mastercylinder and noticed the top of new Mastercylinder says to use DOT4 and My bike took the DOT 5. I spoke with the servive dept and they had told me to use the DOT 5 since my hoses and caliper were filled with DOT 5 and the mastercylinder was new. thats possibly how come the lid says DOT 4

 

I said flush the system not mix the two fluids together and ride for awhile to see if it gels. If you just wish to change from one type of fluid to another, all you need to do is flush completely. I do agree if the two are mixed and you would have more problems. Mixing is not draining, a little bit of DOT 4 left in the system, and then flushing out the little bit left over. Mixing would be having a low master cylinder and filling it with the wrong type.

 

2006 was supposed to be the DOT 4 changeover year for Softails.

 

My guess is that someone replaced the resevoir cover. Since parts most times cover multiple years of bikes it probably just had the wrong thing written on the cover for your bike. It could be right for another bike that it fits.

 

Ya I can second that for sure. And third and forth. The powers that be at work (who obviously were never mechanics) got the bright idea to switch from 3 to 5 in our fleet in spite of our protests. OMG what a nightmare that caused for the next 2 years. I've never done so much brake work in my life. Well, somebody finally got a clue and the Dot 5 went away. Miracles of miracles, so did the brake work.

 

Mine takes DOT 4 and it's a 2006, but this may have been the first year of the change. I wish I had DOT 5, but don't really want to go through all the hassle of disassembling calipers, etc.

 

Just my opinion, but I wouldn't do it. Yeah, you can, but it is difficult at best to get ALL of the residue from the old fluid out even when you rebuild everything and if you don't, it turns into a kind of nasty lumpy goo over time, kind of the consistency of spoiled milk chunks. (Im thinking of 3 to 5, not 4 to 5- I assume that would do something smilar) Not sure what the advantage would be. I guess the idea behind Dot 5 is not drawing moisture from the air? Dunno.