DOT5 or not? (1 Viewer)

[Dagha Boy]

Looming in the near future is bleeding the brakes and clutch on the Dagha Boy.

All new components, pipes etc, so a totally clean virgin installation.

I worry about getting nasty brake fluid on the paint and it's bound to happen as I am less than experienced at it and it's bound to be a battle as I hear that they are a bugger to bleed and have to be 100%.

That got me to thinking about DOT5 silicon fluid for no other reason than the paint. I've read a bit on the net and it seems that there is nothing really against it excepting that you can't ever mix with other than silicon fluid. It is mentioned that it is preferred by professional vehicle restorers for the very reason that it does not harm their paint work.

Does anybody have any experience and/or advice on using DOT5.

 

[1911]

DOT 5 is not hydroscopic, i.e. it does not absorb water like DOT 3 and DOT 4 will. Not a big deal if you are a racer and flush your brake fluid all the time, but if you're going to leave it in for a long time then you risk rust in cast-iron cylinders and steel brake lines. Also it is a lot more expensive and largely a waste of money since you are unlikely to see the brake temperatures on a 40-series Land Cruiser that race cars and bikes have.

The last thing is, you can't ever mix it with DOT 3 or DOT 4, so if you need any out on the trail or in Bumfvuck, Kansas and no one has any DOT 5, you are screwed.

Stick with DOT 3 or DOT 4.

 

[White Stripe]

Why is getting brake fluid on the paint bound to happen?

 

[Dagha Boy]

It just always does with me. Clumsy bugger.

 

[emac]

Stick with 3/4 and buy a bunch of shop rags.

 

[White Stripe]

It doesn't immediately eat the paint. It takes quite a while. Just spray any that's spilled with water. Water neutralizes it.

 

[DougAustinTx]

Dot 5 silicone fluid will never support rust in your lines and cylinders, unlike Dot 3 and 4. Be sure to take all your new components apart before installation and use brake cleaner to clean them before re-assembling them using Dot 5 as the lube. You don't want any residual DOT 3 or 4 in the system, at all. I have used it in my collectable vehicles for 20 years.
It is not all that expensive if you find it on Ebay (the U.S. military uses it in most of their vehicles and they sell off their old unused stock regularly... perfectly good silicone brake fluid, but those are our tax dollars at work.)
If you buy it by the gallon on E bay, don't buy the stuff sold in plastic bottles. The plastic leaches the purple color out of the fluid. Get it in the cans. Also, not all DOT5 is silicone, so be sure to get the silicone version.

 

[Splangy]

As somebody who paints quite a bit, I have a much greater fear of errant silicone based solvents causing fisheyes than I do of brake fluid eating paint. Good modern automotive paints aren’t affected much by brake fluid, anyways. I’ve left DOT 3/4 on wheels for months that were painted with acrylic urethane and it didn’t affect the paint at all.

 

[emac]

You also have DOT 5.1 that is compatible with 3/4, glycol based, and doesn't absorb water. 5.1 is NOT compatible with DOT 5. That may be something to look into. For me I just use DOT 4 and flush brakes every couple of years.

 

[Dagha Boy]

Thanks everybody. Seems to me that the cons outweigh the pros. I will just have to be extra careful.