Dot 3 Brake Fluid

[eamonnpetty]

I just went to the store and bought some dot 3 brake fluid to top off my cars level (2009 Volvo s60 2.5t). Looking at the cap for the brake fluid in my car it says, "Warning. Only use dot 4 brake fluid". But is it really all that serious or should I go back to the store and pick up some dot 4?

[jimmy57]

Go get DOT 4. If your brake pads are worn and the level is above the low line on res then don't add any. The brake fluid level goes down as the pads wear as the caliper piston greater extension increases the volume of fluid held in each caliper. If you add when pads are worn then when pads get replaced and the pistons get pushed backed into bores the fluid returns to res and runs out onto inner fender.
The level will go to a little below half way when pads are worn to minimum level. If it gets low enough to be of concern the fluid level sensor will turn on a warning.

[eamonnpetty]

Thats the reason I bought the fluid. I had a low level warning pop up. Should I add a little or wait until I replace the pads?

[MoVolvos]

Thats the reason I bought the fluid. I had a low level warning pop up. Should I add a little or wait until I replace the pads?

Most generic fluids are DOT 3 & 4. See if yours is for both. If not get a turkey baster and remove and replace with DOT 4.

https://www.amazon.com/s?k=turkey+baste ... _ss_i_4_13

Slower but less messy - Can attach a tube

https://www.amazon.com/Medline-Sterile- ... 173&sr=8-7

[MoVolvos]

-
I prefer to fill up and then remove some before working on the brakes.

[abscate]

You shouldn’t ever add brake fluid To a maintained car because:

You replace the brake fluid every two years per the manufacturer schedule.

In two years, unless you are a taxi, you wont use enough brake pad to cause the level to drop.

When you replace it every other year, fill to the max mark and out a black sharpie level marks o you can monitor it for fluid loss.


Fluid loss means park car.

Pull that DOT 3 out and replace with DOT4