MG ZR: Cams & Maps

[powerandtorque]

The dot4 you linked to will boil sooner than 5.1.

Don't confuse ordinary DOT4 and Super DOT4 (aka Racing DOT4) fluids.

Super DOT4 is typically higher dry and wet boiling point than DOT5.1

Quick example figures (figures in degrees C):

DOT4 - 230 dry and 155 wet
DOT5.1 - 260 dry and 185 wet
Super DOT4 - 300 dry and 195 wet

As you can see, it pays to keep fluid fresh as older fluid that's absorbed moisture has a considerable lower boiling point.

That said, as others have said, you won't have boiled fresh DOT5.1 fluid on track with ordinary pads - the pads will fade long before the fluid boils and it's not like Castle Combe is a particularly hard track on brakes in my experience.