• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Synthetic brake fluid, OK?


Well-Known Member
Local time
12:00 AM
Nov 16, 2020
Reaction score
Elephant Butte NM
Is it ok to use synthetic brake DOT 3 brake fluid in my '63 Dodge 330? I know silicone is bad, but what about synthetic?

DOT 5 is silicone fluid. It does not mix with conventional fluid. It is a pain in the neck to use and I don't think it is used much any more-maybe in show cars that don't get driven much?

DOT 5.1 is conventional fluid and will mix with 3 or 4.
I'm using DOT 5 in my 73.

My master cylinder is still painted black and my firewall/cowl and inner fenders are still body color.

It was a little on the expensive side and I was already installing an new M/C, calipers, wheel cylinders, and front lines. The rears were just blown out and then brake-kleen-ed.

So far, just a tad bit more pressure (power) and the pedal presses down a bit more.
All dot3 is now marketed synthetic dot 3
I used silicon fluid when I built my '64 Polara 500 convertible with no problems. I realized that it did not play well with other fluids, but all brake components were new. Since I am now also putting all new brake stuff on my hardtop, I will be using it again. I like how you can't use it as paint remover.
i have been using dot 5 for a long time no issues at all. The complete brake system was fresh, lines, hosed calipers etc. No issues.
I tried Dot 5Couldn’t get any brake pressure. Went back to dot 3 Problems Went away