Using DOT 4 Brake Fluid in a Honda

JonnyRotten

JonnyRotten

Well-Known Member
1,673
771
Mississauga, Ontario, Canada
Vehicle Model
Civic Si
Body Style
coupe
I just read on a FB group that I belong to that you cannot use DOT 4 brake fluid on our cars.
I've never heard this before so I'm wondering if anyone else has heard this or has some expertise or experience with this.
Apparently if you use DOT 4 it will create some major issues and then you have to replace the brake master etc.
 
I have heard that Hondas are VERY picky about what fluids it takes, Coolant, Transmission fluids so I wouldn't be surprised if the cars don't like DOT4.
The owner manual says:
"
If the specified brake fluid is not available, you should use only DOT 3 or DOT 4 fluid from a sealed container as a temporary replacement.


Using any non-Honda brake fluid can cause corrosion and decrease the longevity of the system. Have the brake system flushed and refilled with Honda Heavy Duty Brake Fluid DOT 3 as soon as possible. "
 
I've been running the ATE type200 for a couple of years now. Its DOT4 and I have not had any issues. Some of the fluids do readily absorb more moisture from the air which can lead to corrosion. A lot of the high performance and high temp fluids do this but they are also supposed to be changed out at least once a year.

Mine gets flushed at least once a year. A lot of the guys running the MotulRBF600 and similar fluids should be changing theirs more often but probably aren't. Honda most likely puts that note in the manual about the Dot4 to cover themselves from people swapping to "track day fluid bro!!!" and never changing it out. Then they try and get their brake system warrantied.

Tons of people run their OEM fluid for way too long anyways. That stuff does absorb moisture and gives that spongy pedal feel. Most people don't know the difference and assume that brakes are supposed to feel like that. If you want to run Dot4, go for it. Just understand what you are getting and what the new maintenance requirements will be. Also flush your system well and be sure to get all the old fluid out.
 
@Nix When using DOT 4 fluid as clutch fluid, should that be flushed like the brake system or can it go longer between flushes?
 
Ok so here is a good question. When i bled my clutch after doing the cdv delete, i used this
89016680_vlv_601457_pri_larg.jpg
It's synthetic dot 3/dot 4 brake fluid. Why wouldn't you be able to use dot 4 if this is both?
I can understand not being able to use dot 3 in something that called for dot 4 because of higher boiling points but why wouldn't you be able to mix dot 3 and dot 4 if it calls for dot 3? Other than the maintenance schedule.
 
The problem is not putting dot 4 in a dot 3 system, it's putting dot 3 in a dot 4 system. Dot 3 has a lot lower boiling point than dot 4 so a system designed for dot 4 only will boil off the the dot 3 fluid and cause major issues/not work. You can put dot 4 in any dot 3 system, it's actually an upgrade to get a slightly stiffer feel and better for heavy braking when temps start to get higher. Your fine
 
And as far as mixing as I re-read your post acknowledging that you know the boiling points lol the dot 3 that is mixed in with dot 4 will just boil quicker so unless you get it hot enough to boil off the dot 3 there's no issue in mixing.
 
Oh and for the people that say we "can't" use dot 4 in our cars, go read the top of the clutch reservoir cap and tell me what it say's. Obviously those people shouldn't drive if they cant read lol
 
I saw that on the clutch reservoir that's why i didn't think it would be an issue but didn't think to look at the brake reservoir. I would only assume it would say the same.
 
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