Tell Tale signs
 

What are some tell tale signs that a rotory might need to be rebuilt?

Without diagnosing the engine and just driving around, a general lack of power. Leaking oil. Burning a lot of oil. Emissions failure. White (coolant) or blue (oil) exhaust. I have no personal experience, but when a rotary needs rebuilt it usually makes itself known.

If you have the time to diagnose it, have a compression test run (expensive) or do the 3-pulse trick. Like any engine, check the plugs for fouling and proper spark. Have a peek at your cats, a clogged cat will cripple the engine.

What is going on with your car? If you're asking about it specifically tell us what its doing. Odds are its something simpler.

The aforementioned oil smoke is one, mainly the only one. Rotaries tend to run excellent right up until the point they quit, and even then when they quit you can usually drive 'em if you don't mind incredibly horrific fuel economy and about 25hp, running on only one rotor.

Mine has started smoking at high RPM's, though it doesn't smoke on startup. (Figure that one out.) Anyhow, I know that I have to prepare to pull the engine sooner or later, but until then it still runs great, starts easily and makes good power.

Don't worry about your motor going until it's gone, just make sure that you're prepared.

Sounds like the neoprene oil seals on the sides of the rotors are on the fritz.

That's what my engine is doing. If I go WOT up through the first three gears and back off, there's a cloud of oil smoke thick enough to walk on. But ONLY if you go up through the three gears - you can't just be going 90mph and shift into 3rd.

Engine has only 166k on it. Think I should go to Mazda and demand free repairs? I mean, jeez, it's only 19 years old, only 166kmi, and it probably only has another 100-150k left in it.