Engine oil ZIC or IDEMITSU

I use idemitsu rotary 20w50

I stick to Idemitsu. I have a Sohn adapter fitted, so it's 10-30 Idemitsu in the engine, twice a year and Idemitsu Premix in the Sohn adapter and in the fuel tank.

I don’t use the Mazda-branded version, but Idemitsu is my go-to oil in all of our Mazdas

Idemitsu is the only premix and engine oil I’ll use ... you can order it for a good price from TREx performance out of NJ and he will ship

The oil was Idemitsu Synthetic 0W-20 with 12.5k miles on it. Once again, trace metals and flashpoint were within normal range. I also ordered a TBN to measure the amount of additive left and that showed there was still plenty of active additive remaining.

In terms of oiling, get a sohn adapter so your apex seals aren't being lubricated with crankcase oil, and instead are injected with rotary-specific oil, like idemitsu.

Subaru OEM oil is Idemitsu 0W-20. I currently use Idemitsu Zepro\* 0W-20, a high-moly formulation from the same manufacturer.

That's the wrong oil. You want the Idemitsu eco gold medalist advanced moly 0w-20, which is basically the same as Mazda oil(Idemitsu makes the mazda oil).

Idemitsu zepro eco medalist advanced moly 0w-20. Basically the same thing as Mazda's oil.

You don't need to add any more additives to modern day oils. You said you will be using Mazda 0W-20 oil? This is one of the best 0W-20 oils on the market. It is made by Idemitsu for Mazda. It has very high Viscosity Index of 221. Most 0W-20 oils are around 170. This means it is one of the lightest 0W-20 at start up. This is what you want in the winter.