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View Full Version : Brakes: Dot 3 or Dot 3 Synthetic ?



Harv
07-22-2012, 08:56 PM
I run Dot 5 Silicone Brake Fluid in both of my cars so I couldn't answer this question from a car buddy of mine. He inadvertantly purchased Dot 3 Synthetic Fluid and was wondering if it is compatible with standard Dot 3 fluid. I believe that they are nearly the same and are compatible but wanted to hear back from you gents just to be sure.

Thanks for the help, Harv :confused:

52 Ragtop
07-22-2012, 09:29 PM
I'm pretty sure they are compatible, I'll double check tomorrow! I sure hope they are! as that's what I used in my Avanti last year!

Jim

nibbs53
07-23-2012, 10:43 AM
Good morning Harv. Dot.3-4 and 5.1 Are not compatible with synthetic brake fluid.
Do not mix them.

nibbs53 Patrick.

Harv
07-23-2012, 01:49 PM
Jim / Patrick .... thanks for the followup. I did just read a bit more about DOT Brake Fluids and they did agree that mineral based fluids are not compatible with synthetic types. Thanks again for your help on this. ..... Harv

sweetolbob
07-23-2012, 01:54 PM
It would appear that there is some confusion about the classifications versus the definition of synthetic.

A Google search will quickly show that All Dot 3/4 classifications whatever the other definitions included are, By definition, compatible. As are the Dot 5.1 fluids. They are all manufactured and formulated for compatibility.

Dot 5 is the lone out-liar due to it's silicone base. If you really look at the definition of synthetic, All brake fluids are because they all require modification of a base structure. Why the industry has allowed this to happen is beyond me. Probably more marketing hype than fact.

Ref: Bob the oil guy and a plethora of other posts. http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2332203

JMO, Bob