Honestly, the XT and SLX brakes are some of the most impressive brakes on the market for the price—mineral oil, easy bleeding, and reliable options in 4 and 2-piston calipers.

That makes DOT 5.1 brake fluid compatible with DOT 3 and DOT 4 fluids, but it follows the same rule outlined above — DOT 5.1 fluid can go into a DOT 3 or a DOT 4 system, but you should not put ...