DOT5

I'm thinking about converting to DOT5. Is it possible to flush the old fluid out(DOT3) with DOT5 until there is only DOT5 in the system? Or would I need to replace hoses and seals? I will be rebuilding the master cylinder anyway.

Sure you can do that. I'm sure there will be argument "they don't mix". The truth is you can pump most the dot3 out until the master cylinder is near empty, add dot5, repeat until you're sure only dot5 is being pumped out. I put dot5 in all my old Kawasakis when dot5 was first seen. When was that? I guess the mid 80s. I've never had one brake problem using dot5.

Thanks Ron!

I used to run DOT 5 years ago because I thought that being silicone would protect things better. The problem is on the contrary. Everything I put DOT 5 into corroded. The problem with DOT 5 is that it will NOT absorb moisture. This will cause the moisture to settle out and cause massive corrosion in the places it settles. You would be much better to use DOT 4+ this fluid seams the best of both worlds.

even harley doesn't use it anymore they have switched back to dot4 it may be due to the fact that they have abs now i'm not sure,all i know is they switched back.

Really the only reason I'm interested is the fact it will not mess up the paint on the front master cylinder. I'm due for a rebuild, and it will need to be painted.

RonKZ650 wrote:

Sure you can do that. I'm sure there will be argument "they don't mix". The truth is you can pump most the dot3 out until the master cylinder is near empty, add dot5, repeat until you're sure only dot5 is being pumped out. I put dot5 in all my old Kawasakis when dot5 was first seen. When was that? I guess the mid 80s. I've never had one brake problem using dot5.

ditto,weve had many debates over this but ive never had problems

Same here. I rebuilt my master then flushed out the line and caliper with dot 5. Never had an issue.

I had DOT5 put in front and rear when my brakes were rebuilt in the 80's.
My bike sat for 10 years from '94 ~ '04. When I got her back on the road, the brakes worked fine, no siezing or other problems.

Otakar is right. DOT5 doesn't absorb moisture so the moisture that enters the brake system will "puddle" and cause corrosion. Obviously, some folks here have used DOT5 with good results; maybe they're not in a high humidity environment, who knows. DOT5 high a very high boiling temp and is often used in racing appplications, but racers change their brake fluid often thus purging the water. It's your choice, but in my location I wouldn't risk it. If you stick with DOT 3 or 4 just be careful not to spill it on our paint. Ed

Dot 4+ is a synthetic which should not harm the paint.

just keep the trash flushed out of your system every spring with the dot5 and youll be fine