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RX8 ENGINE BREAK IN PROCEDURE FOR ENGINES ALREADY INSTALLED

  • Keep rpm under 4000 when possible. 
  • Keep throttle position at half or less when possible. 
  • For engines with new bearings installed, change oil at 500 miles. For those with reused bearings, no immediate oil change/flush is needed however it is still not a bad idea. 
  • Change oil every 2500-3000 miles at most. Rotaries tax their oil supply more heavily than piston engines. 
  • NEVER run mazda’s recommendation of 5-20 or 5-30 motor oil. I recommend 10-30 for cold climates and 10-40 or 20-50 for hot summer climates. 
  • NEVER run synthetic oil. 
  • Expect that the engine will refuse to start when warm (after being run and then shut off) during the first few days/couple hundred miles, so plan your first few trips accordingly, hopefully in such a manner that you can avoid stops that would require you to restart the car quickly. Compression in a rebuilt rotary is weak when first assembled and must come up gradually over a period of days and weeks of run time/revolutions on the seals and heat cycling. After you put some miles on the engine it should begin to respond better, at which point you can begin shutdown and warm-restart without as much worry. 
  • Do not crank excessively when attempting to warm-restart (and failing) or you’ll flood it badly and foul your plugs, which are no fun to change. If it doesn’t start within 5 seconds, it probably isn’t going to. Let it cool off longer and try again later. It can usually take 1-200 miles of break in, sometimes more depending on the parts used, for these engines to get to the point that they will warm-restart fairly well, and 1000+ in some cases before the warm-restarts become quick and crisp. 
  • Sometimes when cranking (and failing to start) it is useful to employ the fuel-cut feature of the computer. To do this simply floor the gas pedal while still cranking, this cuts the fuel injectors off and will keep the engine from flooding worse during cranking. Sometimes it takes a bit of fooling with the gas pedal position on/off during cranking to clear a light flood condition and/or help warm-restart until compression becomes stronger. 
  • Run engine for approximately 1000 miles before opening it up to full rpm and throttle. The break in time varies based upon the parts used in the build, and each car has it’s own personality. When the engine begins to start crisply when cold, idle smoothly, restart when hot within 2-3 seconds, and have good low rpm pullout/response, you can consider it mostly broken in. The only way to be certain is to run periodic compression tests and wait for the numbers to level off and stop increasing, at which time you can be certain break in is complete. 
  • After the engine is broken in (approx 1000 miles or so) and is running normally, install a new set of spark plugs. 
  • After the engine is broken in (approx 1000 miles or so) and is running normally, I suggest beginning a 2 cycle premix routine. This will help to overcome the rx8’s insufficient lubrication issue and hopefully offer improved engine longevity (depending on what parts were used in your build). To do this, simply obtain a 16 ounce bottle, and also a gallon jug of any standard 2 cycle oil (the same kind you’d use for a weed eater or outboard boat engine). The 16 ounce bottle is used to keep in your door pocket for easy measurement and mixing for each fillup, the gallon jug is an economical way to refill that bottle. Simply pour the bottle into the gas tank and then pump your fuel. This will provide you with at least 1 ounce of oil per 1 gallon of gas which is the minimum ratio I’d recommend for this car. IF you notice that your routine fill up only requires (for instance) 12 gallons, then you can trim that bottle refill back a couple of ounces. This procedure has no known disadvantages, and the potential to extend the life of your engine and prevent premature internal wear, and it can cost as little as $1.50 per fill up, which is cheap insurance compared to what you’ve just spent for a rebuild.