DOT4 vs DOT3 Brake/Clutch Fluid

[wolfie359]

I know that with BMW and Audi's your suppose to use DOT4 Fluid. The rest of the cars in the world use DOT3... Whats the difference between DOT4 and DOT3 Brake Fluid and what can happen if you use DOT3 instead?

I think that the previous owner of my car used DOT3 when they replaced the clutch master and slave cylinders, but now I seem to be having a clutch hydraulic related issue and was wondering if this may be part of it. Haven't torn into it yet, just kinda wanted to get an idea...