DOT3 and DOT4 are interchangeable.  DOT4 is a newer formulation and, as
I recall, will take heat better.

DOT5, on the other hand, is NOT compatible with 3 or 4 and must be
avoided at all costs!

Mike

wogdog wrote:
> I'm ashamed to admit that after owning my Westy for 5 years that I have been using the wrong DOT in my hydraulic system. I changed out the clutch master and slave cylinder's today and as I was wiping up a spill on the reservoir I noticed "Use only DOT 4" on it. What is/are the differences between the two? Am I screwed? But then this is the first time I've had a problem with the system in 5 years.
>   TIA,
>   Paul Rogers
>   85 WWW
>