No NA or NB MX5, from the factory, open, viscous, Torsen T1, Torsen T2, Fuji, needs “LSD oil”.
Some imports might have an aftermarket (typically Kaaz) clutch-type LSD, and that will need a specific oil.
The change quality changes by year, and is hit and miss. Redline might make it feel better, or it might not. Some cars will benefit from having the shift bushes renewed, so won’t.