[Bob Broberg SPF667 460BB]

Dot 3 is $5.99 a quart and Dot 4 is $7.99 a quart. You guys change your brake/clutch fluid often enough AND you don't race on a track so Dot 3 is just fine. Dot 4 can handle higher temps as we all know. Dot 4 can be used to replace Dot 3 in all cases but not the reverse IF your Mfr recommends Dot 4.
Dot 5 is for LeMans.
AZ Bob