Yeah VMX80 is the right one. I spent time researching this and the official Nissan recommendation for the similar gearboxes that were Aus delivered still recommended Castrol VMX80. That is the equivalent to what the cars such as N13 pulsar LSD came with. Works great, you can really feel the LSD lock/bite when exiting corners and putting the power down. The LSD was awesome for exiting corners with under power, that's where I really noticed the biggest benefit. Apart from that, I was never sure if I could notice an improvement in just everyday power launching off the mark standing still. But it really changes the way the car exits a corner under power compared to the factory open LSD rubbish.
The specialised LSD diff fluid yeah is for the mechanical ones.
I have gotten to know the ASC electronically controlled setup in the colt more now. Basically, its nowhere near as good as a proper LSD and nowhere near as good as the VLSD in the micra for exiting corners. I think the Colt accelerates off the line cleaner and faster than the VLSD micra, it seems fairly ok in terms of launching traction control. But under power during corners, its really just a normal open centre diff with some electronics over the top that kick in and out like an ABS style thing, except it actually puts more power to the gripping wheel which is good. But it doesn't have a fantastic super grip feel to it like a proper LSD. Ralliart made a proper mechanical LSD for the cars now, but in my opinion that should have been a factory item.