OEM Mazda fluid is about $15 a quart. Why not just use the OEM fluid and sleep better at night? The fluid change interval can’t be frequent enough to be sweating about the slightly higher cost. Are you looking to save $10 to $50 over 60,000 miles? It hardly seems worth it.
IMHO the best bet with coolant and especially tranny fluid is to use only OEM fluids.
Try other fluids and you risk coming back here asking how much it costs to replace a transmission.
The most knowledgeable people for your car’s needs are the engineers that designed and tested it. And the design team are the ones that created the spec sheet from with the tech writers that wrote your owner’s manual got their information. Nobody on any internet site knows better than they what’s best.
The computer that controls a modern automatic transmission or transaxle has its algorithms based on fluid with very specific characteristics. Stray from those characteristics and the result could be anything from rough shifting to the very early demise of the clutches.
Honda Trannys have been weak - so I have been using Honda ATF every 2yrs on my Hondas - because Mazda said type M5, I was thinking another M5 might be better. It looks like I will be continuing with the OEM fluid then.
Having moved to Synthetic for engine oil (including on my 80s honda), I somehow had a mindset to use another fluid - especially one is better (synthetic), costlier, what enthusiasts are using etc.
I wouldn’t necessarily call them weak because the manual tells you to change the fluid in them 2yr/30k miles. They certainly are more picky in regards to the type of trany fluid, that is true.
