View Full Version : Ever Wonder Why I Use Dot 5?

08-20-2018, 02:45 PM
Just in case some dumb arse leaves the cap off the master cylinder when he's reverse bleeding it.:mad:


A lot easier to clean up then to repaint.


Skip Lackie
08-20-2018, 04:02 PM
Thanks Bob. That's one screw-up I haven't actually done myself. (But I also use DOT 5 in everything.)

Mike Van Veghten
08-20-2018, 04:10 PM
Just flushed one bike and one car in the last coupla weeks.
I still use real brake fluid (DOT 4).


08-20-2018, 07:00 PM
I use DOT 5 in both of my Studebakers. I like that DOT 5 doesn't attract moisture like others do.

08-20-2018, 07:29 PM
I like DOT 5 after helping a friend pull a '64 Hawk out of a garage where it sat for thirty + years, and the brake system had zero stuck wheel cylinders/master cylinder, no leaks, and simply required a fill and bleed to get them working again.

08-20-2018, 08:32 PM
Dot 5 in everyhting I own for the past 40 years!

Mike Sal
08-20-2018, 08:44 PM
No problems with brake switch failures?

08-21-2018, 08:17 AM
My R2 had a dot 5 conversion done in 1985 when it was restored. Brakes work great. It still uses the brake switch that came with the car when I got it 5 years ago but I can't say how many switches the previous owner, and there was only one since the rebuild, had to replace before he got it right.

08-21-2018, 08:24 AM
Perhaps the question here is, how does it work as a glass cleaner?

Skip Lackie
08-21-2018, 09:06 AM
Have had DOT 5 in 5 or 6 vehicles since 1978. One brake light switch failure in one vehicle after about 20 years of use.

08-21-2018, 09:19 AM
Perhaps the question here is, how does it work as a glass cleaner?

Or maybe a paint polish?

08-21-2018, 09:37 AM
Perhaps the question here is, how does it work as a glass cleaner?

:D Actually pretty well, not on it's own but the wiping with denatured alcohol, Prep-sol and Glass Magic cleaner makes for a quite clean windshield.:cool:


08-21-2018, 07:12 PM
Ok, so I’m still using dot 3 fluid in my Stude but the system is mostly empty as I had the wheel cylinders sleeved and remade all the steel lines. So how do I convert to Dot 5 in my car?

08-21-2018, 08:25 PM
Flush the entire system, then install DOT 5 and bleed the system.
I've been changing all my old cars to DOT 5 since the 70's, whenever I do a brake job.

Skip Lackie
08-22-2018, 07:06 AM
If you have replaced the steel lines, I assume you are also replacing the rubber hoses. They should be replaced any time the system is opened up. If it's "mostly empty" flush any remaining old fluid out with a good solvent (acetone, lacquer thinner), followed by compressed air to dry it out. Follow with a flush with a little DOT 5 to get anything still hiding in there.

08-22-2018, 07:48 AM
After cleaning up my issue, I'd suggest using denatured alcohol to flush the system and then also some Dot 5 before sealing up the system. Lacquer thinner and acetone are bad for paint and rubber. If the system has no rubber parts then my choice would be acetone. Mixes with water so it would remove any moisture in the system, it should be a pretty good solvent Dot 3/4 and would remove any grease and oil also.


08-22-2018, 10:55 AM
Any alcohol based solvent such as those mentioned or methyl hydrate, methyl alcohol, etc will dilute and flush glycol based fluid. There is an issue here that one has to be aware of. When you flush the wheel cylinders it is not easy to clear ALL the glycol fluids out as some could find a nook in the ends at the cups to hide in and when you introduce DOT 5 fluid you can get it mixing and creating a large lump of goop in the cylinder itself. Be VERY sure of clearing all the old stuff out of your wheel cylinders.

08-22-2018, 10:14 PM
The wheel cylinders are dry and rebuilt. No fluid in yet. I did replace the hoses a few years ago when I began the restoration. So flush with denatured alcohol and then dot 5 before filling and bleeding with dot 5

08-22-2018, 10:30 PM
If the wheel cylinders are dry and installed with pistons and rubber parts, then I'd disconnect the lines at each one when you do the flush. This way you won't have any chance of the flushing fluid remaining inside the cylinders. That's the way I flushed my system.

BTW, when I rebuild the master and wheel cylinders I coat the cylinder and parts with DOT 5, so they are lubricated and don't flash rust.

08-23-2018, 05:43 AM
Good thinking! I had my wheel cylinders sleeved with stainless steel to avoid rust issues.