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Brake Fluid - Synthetic or Mineral?
  • joe53HHjoe53HH
    Posts: 11Hitchhiker
    I originally posted this message in the GENERAL area by mistake (First time posting to the Forum!) SO here goes take 2.........

    I want to flush out the old fluid from the brake system in my 53 Hornet. I know enough to stay away from the DOT-5 silicone fluid but I wonder what your thoughts may be concerning the DOT 3 & Dot 4 fluids. I see all contain various formulas of glycol but some are synthetic and others are mineral based. Your opinions will be appreciated. Thanks, Joe
  • Terraplane33Terraplane33
    Posts: 234Gold Member
    Is there a specific reason to stay away from the DOT 5 Silicone ? :huh:
    Location : France
  • 53jetman53jetman
    Posts: 873Platinum Member
    Have used DOT 5 Silicone for years without any problems. For best results you must initially use in a completely new system - new wheel & master cylinders and new hoses. Flush the existing metal lines with brakleen to be sure you get all the old DOT 3 or earlier fluids cleaned out.

    Jerry
    Jerry
    email: HudsonJetman@mail.com
    2nd Generation Hud-Nut
    HET Tech Adviser on Hudson Jets 1953 & 1954
    HET Registrar of all Hudson Jets
  • joe53HHjoe53HH
    Posts: 11Hitchhiker
    Because I plan on using the existing brake lines I want to avoid even the slightest possibility of a fluid type contamination. That is why I do not want to use DOT5 fluid. I haven't read anything regarding the advantages/disadvantages between the mineral based and synthetic DOT3/DOT4 fluids. The manufacturers usually state the synthetic fluids are compatible with other DOT3/DOT4 fluids.
  • Jon BJon B
    Posts: 4,770Moderator
    Actually, you've posted your questions in the "Discussions" section of the Hudson Forum. That's where people go for jokes, rants, and messages not related to Hudsons. The "Hudson" Hudson Forum is at http://classiccar.com/index.php?option=com_kunena&func=showcat&catid=13&Itemid=129 and you might want to bookmark it when you get there. (It's REAL easy to get lost trying to navigate the Classiccar forums!)

    You may find someone at the Hudson forum to answer your DOT 3 versus DOT 4 question more directly, since more folks hang out there. Unfortunately, I'm one of those who tried silicone in his car 15 years ago, and never looked back! The fellow doing the conversion merely blew the lines out with an air hose, poured the silicone in, and I haven't had a lick of trouble since. Only danger with silicone is that it sometimes manages to leak out of the brake light switches. I'm driving a '37 which has a primitive mechanical brake light switch so...no problem!