How about using dot 3-4 brake fluid. No place around here sells dot 4 or Castrol synthetic brake fluid. But they sell valvolean 3-4. Will that do or will that be as likely to ruin the system? Yes I'm going to do a full flush before I add the new fluid.

 

Valvoline 3/4 should meet the Land Rover spec. I use Napa DOT4. I thought it was available everywhere. The racing fluids I mentioned are like Motul 600, Wilwood, Tilton. They run around 590F dry boiling point. DOT 4 is 446F. Maybe more important is the wet boiling point. DOT 4 has to meet 311F. Motul for example is 420F. Another really good one is ATE Super Blue. That's what you use if you race Porsche for example.

 

They put 3-4 on the bottle for people looking for DOT3. That way they know they can use it in either system.