If you look at the differences between the WC and Standard T-5 it seems plausible that you should use different lubricants. The WC has journals, brass synchronizers, and straight roller bearings whereas the Standard has needle bearings, fiber synchronizers, and tapered roller bearings. I still think the best bet is to consult the owner's manual for the vehicle the T-5 came out of. One important fact that I don't think anyone has posted here is to not mix lubricants. If you decide to make the swap from gear oil to ATF or vice versa flush the transmission first.