This is a 83 rx7 5 speed, While changing the engine oil for the 1st time, I could not find the drain, I loosened this side plug/bolt and a little oil came out. So I thought it was the tranny filler. Now I'm not so sure what it is. This Pic is from under the driver side door. You can see the engine oil pan. What is that big bolt for? SC

 

Looks like the rear iron banjo bolt for the oil cooler line. You must have a beehive oil cooler directly below the filter.

The drain plug is located on the passenger side of the oil pan.

 

https://www.rx7club.com/1st-generation-specific-1979-1985-18/download-copy-your-year-fsm-click-thread-get-link-894736/

 

that is the banjo bolt on the rear housing. supposed to have an oil line connected to it either by way of the bee hive oil cooler or a front mount cooler. the oil drain plug, like on all vehicles, is on the oil pan. in ur case, it's on the pass side. tranny filler and drain plugs r on, of course, the tranny.

 

What a relief! I took that bolt out and a few drops of oil dripped out. I about had a heart attack that I did not have any oil . Screwed it back in and found the real drain plug. whew.. what a relief..., oil that smelled like fuel came out. Carb floats were stuck..Now fixed... then I'm driving along and the oil chime alarms.OMG. I'm leaking oil like a stuck pig! Coast into a jiffy mart and pay 8 bucks for 2 quarts of sub par oil. I'm thinking that the rear main seal blew or I cracked the block... "Does a RX7 have a block?"... Today.. I think I did not torq that bee hive cooler bolt hard and the oil pressure was blasting oil around the loose bolt. Next round is on me!... thanks SC

I get the feeling that bee hive coolers are not that cool.

 

Beehives suck. They are marginal at oil cooling and very leak prone.

Thankfully, retrofitting the proper front mounted oil cooler is as easy as bolting the cooler up and connecting the lines. Mazda gave up on the beehive very quickly.