The DS was getting low on break fluid and I have DOT3 that I used in the Polaris and cars,, I never have heard of DOT4? Is it cleaner? Will DOT3 work to top it off? Or should I just NOT be cheap and go buy the dang bottle?

 

Dot 4 is a higher quality,it has a higher boiling point,therefore a better operation range than Dot 3,you can top off with the 4,but it wouldn't take much to just bleed out and refill with the Dot 4,so if you have time,go ahead. I have been using Valvoline synthetic brake fluid,it is rated Dot 5,and it is compatible with 3 and 4.

 

From what I understand, you can use a higher DOT # in something, but not lower. Meaning you can put DOT 4 where DOT 3 is called for, but not a good idea to put DOT 3 where DOT 4 is called for. This is what the Autozone guy told me.

 

The higher the DOT # the better the fuild. Better in this case means it can handle more hear and preasure. My hydro brakes on my blaster use DOT 5 fluid. It cost almost $20 for 16 oz. I would just spend the extra money for the recommended DOT # your brakes call for.