2001 GMC Yukon XL (Aka Beast)

[Bigburb3500]

I decided to check upon my dot 3. It smells like bog. I don't know how to bleed brakes. So I used a syphon, and added new Prestone dot 3 max. Filled reservoir till max. And then started vehicle and pumped brakes few times. This is cool in reservoir after I changed it. Probably I will do a procedure few times and then go to repair shop for new pads and properly bleed them. And flush brake fluid again. I just want to do what our shop will not do. They never washed brake lines, they never wash engine. So I will buy some 5w30 pensoiol and wix filter. And do procedure again. Just waiting for abs module to show up. I decided not to take it apart , and go and order the cheapest one from Rock Auto.

Definitely time to do brake fluid! Brake pads are super easy on this truck but if they haven’t been done in a while the salt might make the job a bit difficult.

 

[Fless]

No harm, just advantages, in using DOT 4 instead of DOT 3. It has better qualities, so consider having them use DOT 4 when flushing the brakes.

 

[makintoshnex]

No harm, just advantages, in using DOT 4 instead of DOT 3. It has better qualities, so consider having them use DOT 4 when flushing the brakes.

What about mixing dot 3 and dot 4? Will it go bad? I saw in AutoZone some universal dot 3 and dot 4 in one bottle. What is the difference between?

 

[Fless]

What about mixing dot 3 and dot 4? Will it go bad? I saw in AutoZone some universal dot 3 and dot 4 in one bottle. What is the difference between?

It can mix with no problem. What they sell in the DOT 3/4 bottles is DOT 4, backward compatible with DOT 3. It's best to do a full flush to get the full benefit of DOT 4 (primarily the boiling point) but either way works.

If interested, a little reading here for comparison specs: https://www.autozone.com/diy/brakes/dot-3-vs-dot-4-brake-fluid