A very common issue with 2nd gen rx7's is for the o-rings on the oil pedestal (the round metal thingy that you screw the filter onto) to detereorate and break. This causes a nasty oil leak, which is especially bad since it's directly above the heater hose. Oil on water hoses tends to weaken them, and if this hose breaks, you will lose your coolant. If this happens, the BEST you can hope for is that you catch it and only are stuck on the side of the road for a while. The worst case is that your engine overheats, breaks, and you're stuck on the side of the road for a while, waiting for a ride, and thinking of ways to earn the money it's going to take to fix your engine. :)

Luckily, these o-rings are cheap, and easy to replace. You can pick them up from your local dealership, mazdatrix, or even a local auto store. The installation is rather straightforward, and is only complicated if you have large hands, as the work space is VERY restricted. The whole process, including oil change, should take ~30-45 minutes, the first time, going slow, taking pictures.

This is what you must purchase. Mazda part #9954-10-1601, or an equivilant. Be sure to get two!
From mazdatrix:
10-1601-9965.....O-RING OIL FILTER.....TOWER ALL.......$3.30

Hmm.. Well, it sorta looks like the outer diameter is roughly 13/16".. Don't take my word for it tho. The inner diameter really doesn't matter TOO much, as there's quite a bit of room, as is shown below, as long as it's not rediculously small so that it gets in the path of the oil. The outer diameter is more important, as you want it to fit snugly into the pedestal recess.

Here we have the oil filter off. A good time to do this maintanence is when changing the filter--you will already have it off. There are two 10mm nuts that hold this piece onto the pedetsal. You must remove them both.

Here is the top of the pedestal. You can see the two bulges where the bolts are, and the bulge in the middle for the oil travel. Unfortunately, I didn't orient the pedestal as it is in the car...mentally rotate the picture about 55 degrees anticlockwise, and that's the orientation as if you were standing on the driver's side looking into the engine bay.

Here we have the bottom of the pedestal. You can see the threads that the nuts are held onto, as well as where the two o-rings matched up to it. When I removed it, the old o-rings were stuck to the base, still in the car. Clean this guy up a bit..

Here is a side-by-side comparison of the old (bottom) and new (top) o-rings. You can see how the old ones are very flat. They are also very brittle, and crack very easily.

Here I've put the new o-rings in the pedestal. Be sure to completely coat them in new oil first! They fit easily, but snugly.

This is the base of the pedestal, still in the car. My old o-rings were VERY stuck to this. The surface is actually flat (the o-rings do not sit in a recessed area on this), so I ended up using a razor blade to remove the old rings. Clean this area off, too. And really, DO NOT let anything fall into the holes!!! If you're worried about this, shove a wad of paper towel into it (not FAR..make it easy to remove), so nothing can slip in.

Re-attach the pedestal, making sure the o-rings don't come out. The tightening torque for these nuts is 6-8 lb*ft. Attach your new filter (you *DID* get a new filter, right?), and go ahead and change your oil....you're probably due anyway. Make sure you put the bolts for the pedestal through BOTH holes! I know it sounds obvious, but with such a cramped area, it's suprisingly easy to miss a hole completely. Start your car up, check for any leaks, and speed away!

*I make no claims as to the accuracy of this. It worked for me, it may not work for you. Don't sue me.*
Please let me know of anything incorrect above! -tesla042