Mine didn't do it new. It developed it after thousands of K's, can't recall how many. I've been happy with the penrite SYN-75W90 (? - check that) as a solution. Yes it's a GL5+ oil, but if you read the specs carefully you'll note that it meets the requirements of the diff and gearbox (often GL5 generally don't), and while I was briefly concerned about long term effects, the penrite is compatible with copper alloys (a GL5 specific concern), and meets the LSD needs. Shifts are cleaner quieter and I've not seen any sign of the LSD struggling because of it. When I uptune, I'll pay closer attention to that again and if I think the LSD is going to struggle, I might pull back to a GL4 and put up with the noise, but I'm happy enough with the penrite for now. I don't believe it's doing any damage. People might slag mazda's support off from time to time, but I'm fairly confident they did their homework choosing the penrite, as I haven't found another GL5 yet that specs as well for use in the MPS.
"Blue Meanie" 2007 Aurora Blue MPS 3 - 18x8.5+44 SSR GTX01 - 235/40R18 Michelin PS5 - 3.5" ETS TMIC - CPE stg 2 mount - HKS/CPE BPV - 2XS inlet - 2XS short shift - Corksport turbo manifold - HT 98 octane tune - Leather/Aluminium handbrake - Momo shifty knob - 7" touchscreen - JDM Mazda Retractable dashtop screen assembly - Bespoke Raspberry Pi Android based GPS/Carplay and instrumentation - 36AH reserve battery and C-TEK isolator - TEIN Street Advanced coilovers 1" drop - Superpro bushings - 220Kw/410Nm.
"Lipstick" 2013 Velocity Red MPS 3 - 18x7.5+48 Enkei RPF1 -225/40R18 Federal RS-RR - CPE TMIC - COBB inlet - CPE stg 2 mount - COBB Stage 1 98 octane tune - COBB shifty knob - 2XS short shift - 2XS turbo manifold.