Hey All!
I recently upgraded the pads and rotors on my 07 2.2L LT to some slotted EBC rotos and DFC Advanced braked pads. I understand the basic differences between Dot 3 and Dot 4 brake fluid but is it safe to run Dot 4in a Dot 3 brake system?

I ask becuase I believe I boild the fluid after getting stuck behind a slow driver and had to ride my brakes down a very long, steep hill (after a bit of spirited back road driving). I figured since Dot 4 has a higher boiling point and it may prevent this happening in the future.

 

Change out the DOT 3 with fresh DOT 3. Check the front flex hoses for bulging, replace them if cracked or bulged. Adjust the rear drum brakes and also inspect the flex hoses back there.

 

Will do! My drum brakes need replaced for inspection anyways.

 

Do you keep the rear drum brakes adjusted? That would help stop overheating.
DOT4 can mix with DOT3, no need to worry about totally evacuating the system.
Don't use DOT5.

 

I do my best to replace them when needed however I admit I haven't regularly adjusted the rear drums aside from replacing them every other year for inspection.

I knew not to use Dot 5 from my autopart sales days as that stuff is silicone based and can cause serious problems with non-Dot 5 systems. When I bleed the front lines I'll definitly use Dot 4 to replace the fluid.

Since Dot 4 is more hydroscopic, how frequently should I be checking the water content in my brake fluid if I run a mix of Dot 3 & 4?

 

For future reference

DOT 4 has a higher boiling point than DOT 3. You can use DOT 4 where DOT 3 is called for, but not the reverse.

 

If you’re going to bleed the system, do the whole thing. All 4 corners. That way you’ll have fresh fluid through out.

 

That makes sense!

 

As FMG said, flush the complete brake system

 

Change rear brakes every year!!!??? They should last 200,000 miles, or 3 sets of front pads. Your money, waste if you want.
I drove min 200-400 miles a day in some of the worst traffic in the country. Front pads lasted 60,000 miles rears got replaced at 200,000 just because.