Non OEM good brand for a thermostat.
 

My car is running without thermostat, so i was looking for an OEM but i cant find any in my country and they are too expensive to buy outside, about 60$ including 6-8 weeks shipments from AtkinsRotary and im not sure if thats really an original because looks like it hansn't the jiggle pin. So, there's any good thermostat brand for a 1986's FC?

And, the ones with a ring instead of a gasket from 89-95 are compatible with mine?

This one from MotoRad looks close to the OEM i think:

The S5 thermostat with the rubber seal is not compatible with the S4 thermostat housing. The thermostat is physically smaller and the rubber seal does not work with the housing or neck. You can try and aftermarket thermostat but some have been known to cause overheating issues. Do you not have a Mazda dealership within driving distance? Have you tried www.mazd-part.com?

Stant is quite expensive in my country for an aftermarket thermostat because it has to be imported, i didn't see much friendship to Stant in this site, you know good experiences with it? Could you tell me what do you use to clean the gasket? And you recomend to use some silicone instead of a gasket?

Thanks, i'll be sure to get an S4 compatible thermostat in that case. I'll be very very carefull before install the aftermarket thermostat, i'll instal new temperature gauget and sensor and i'll change it every time i change my coolant until i could find an OEM if i ever can, i am a bit scared about it after read lot of threads talking about the overheating. I have a Mazda dealership in my city but they havent the piece and they can't order it, i called multiple dealerships in my country and every one telled me that that thermostat is no longer available. Mazda-parts doesn't send to europe :(

My almost only affordable options are this three:
https://cimg6.ibsrv.net/gimg/www.rx7...9978edc7cd.jpg
Nippon Pieces
https://cimg7.ibsrv.net/gimg/www.rx7...71c8d71eb6.jpg
Gates
https://cimg9.ibsrv.net/gimg/www.rx7...6958a280d0.jpg
Vernet

These Australian ones work fine. Pretty trusted brand. I'm running one in mine. Not sure if its cost effective after postage https://www.ebay.com.au/itm/TRIDON-H...r9f:rk:28:pf:0
Other brands Dayco and Gates can be had cheaper. I have no experience with their thermostats but they also make good stuff.

And the only reason I recommended STANT is because I've had OK luck with that brand on an antique car. I typically would only recommend MAZDA for this. And NO, I would NOT recommend silicone in place of a gasket. Clean the mating surfaces really well and use the gasket.

You're welcome