From what I have read there is an advantage to switching to the synthetic DOT 5 expecially on the brake hardware.

 

I'm about to swith all my Bleeder Screws to Speed Bleeders and as I have to go through the bleeding process anyway, I was wondering if this would be a good time to switch to the synthetic DOT 5 fluid.

 

How should I go about draining the DOT 4.........All opinion's and tips appreciated. 

With all the advantages of DOT 5, in order to use it you have to completely flush and purge your hydraulic system of the brake fluid you have now.  I would also replace all flexible brake hoses and seals in the calipers.  Otherwise you run the risk of it mixing with any residual brake fluid currently there.

DOT 5 is also notoriously difficult to completely bleed the system of air.  In fact, many, if not most, makers of performance cars specifically state not to use DOT 5 fluid.  In extreme handling it can bubble and those bubbles can cause spongy pedal.  

My own opinion is DOT 5 is great in a museum car or a car that get driven occasionally and gently.  I think DOT 3 or 4 is better for most purposes.  

There's also a DOT 5.1 which is non-silicone and is backwards compatible with DOT 3 and 4.  It should have been given a different designation as it creates confusion.  

Your money...your choice.

 

I will just install the new Speed Bleeder Screws and continue with the DOT 3/4 fluid.

 

I just bought the '68 in late Oct and the only issue I have is the Brake lite comes on when I push hard on the brakes then goes out.  What I've read, the majority lean toward there being air in the brakes and bleeding being the probable fix.  I live in CO so the driving is winter limited as far as use.

 

I'm putting Speed Bleeders on because you can do the process by yourself, as my wife is never around when I need her.  I've got the Bleeders and the hose and catch bag, so now with this decision made, I'm ready to bleed the brakes as soon as it warms up a bit.

 

This shows how valuable this site is.  Especially for those of us that are mechanically challenged as they take on the more simplier of tasks