Dot 5 brake fluid quick answer needed
Road Warrior
Joined: Dec 2015
Posts: 1,826
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From: Southwest Desert
Flush out completely with the recommended fluid, and fill with the recommended fluid, and re-bleed. Your brake system will be happier for it, and you will never do that again. (I know, you were just asking for a friend) There should be no permanent damage.
Seasoned HDF Member
Joined: Aug 2006
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From: Pennsylvania
Maybe, depends on how much DOT 5 you have, but you have to be sure you got ALL the DOT 5.1 out of the system. The safe bet would be to flush the system with Isopropyl Alcohol air dry (with an air gun) and proceed with flush and bleed with DOT 5.
Mixing DOT 5.1 & DOT 5 will cause the fluid to jell and you will have a mess.
Mixing DOT 5.1 & DOT 5 will cause the fluid to jell and you will have a mess.
Seasoned HDF Member
Joined: May 2008
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From: South Carolina
The problem is that when DOT5 is mixed with DOT3, 4, or 5.1, it will turn to a gel.
Last edited by Dan89FLSTC; Apr 23, 2021 at 03:52 PM. Reason: incorrect information
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Extreme HDF Member
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From: Somewhere SW
When I was in the Marines all of the tac vehicles used DOT 5. I remember one guy puting DOT 5 in his pov. 1500 dollars later he got his brakes repaired, all of the rubber components were swollen and to be replaced.
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HDF Community Team
Joined: Dec 2005
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From: NC USA
Correct (and by the book as well)
Maybe, depends on how much DOT 5 you have, but you have to be sure you got ALL the DOT 5.1 out of the system. The safe bet would be to flush the system with Isopropyl Alcohol air dry (with an air gun) and proceed with flush and bleed with DOT 5.
Mixing DOT 5.1 & DOT 5 will cause the fluid to jell and you will have a mess.
Mixing DOT 5.1 & DOT 5 will cause the fluid to jell and you will have a mess.
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,195
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From: NW AR
DoT5 won't hurt rubber, but the crud it turns into if mixed with 3, 4 or 5.1 might.
Flush the whole system, denatured alcohol will work (sold as "HEET" at auto parts stores,) or brake cleaner, then hit it with the air hose for a while and it will be OK. Brake cleaner will be a lot harder on rubber parts than the denatured alcohol, which is Ethanol (i.e., "drinking alcohol") mixed with enough Methanol to kill you if you drink it, so, you know, you won't be drinking it. I have changed several DoT3 clutch systems to DoT5 this way and had good results. And I use that MilSpec DoT5 fluid in the gallon jugs. Cheaper that way.
Flush the whole system, denatured alcohol will work (sold as "HEET" at auto parts stores,) or brake cleaner, then hit it with the air hose for a while and it will be OK. Brake cleaner will be a lot harder on rubber parts than the denatured alcohol, which is Ethanol (i.e., "drinking alcohol") mixed with enough Methanol to kill you if you drink it, so, you know, you won't be drinking it. I have changed several DoT3 clutch systems to DoT5 this way and had good results. And I use that MilSpec DoT5 fluid in the gallon jugs. Cheaper that way.