Is it ok to mix DOT 3 with DOT 4 fluid?

INFORMATION Integra Help
1

My brake fluid reservoir is low. So I went to Honda dealer and got me some ‘Honda DOT3 Heavy duty brake fluid’ (that’s what it says on the label).

Anyway, I believe what’s inside the already low reservois is DOT4 fluid of some brand I got in Autozone years ago.

Is it ok to just pour the new fluid in? Or should I drain the old one and put in new one and bleed?

Frankly I never bleed fluid before, thus this Q. =P

so HEELLPP.

Thanks.

2

Are you sure DOT4 is already in the system ?
I read somewhere that DOT4 is silicone based
and it’s NOT recommended on our cars b/c
it will eat away seals.
You can do one man bleed by using speedbleeders.
http://www.speedbleeder.com/

3

DOT5 is silicon based, not DOT4. It will be fine to just fill it up. Here is a quote from an article on how brake systems work.

"Different types of brake fluid are used in different systems, and should NEVER be mixed. Most cars use “DOT 3” or “DOT 4” brake fluid. Some newer cars use silicone brake fluids. These should NEVER be mixed together, because the seals in each car are designed to work with only their specific fluid types. For example, the mixing of “Silicone” brake fluid and conventional glycol based DOT 3 or DOT 4 fluids should be avoided, as the two fluid types are not miscible (they will not mix together). DOT 3 brake fluids and DOT 4 brake fluids can be mixed. "

4

yea, dot 3 and 4 are basically the same according to my auto teacher, its the dot 5 that you cant use