Does anyone have the definitive answer the need or otherwise to "run" cars in?
The Mazda Owner's Manual mentions only that the engine should not be run at high revs for sustained periods and I was told by the dealer when I collected my car that it is best to drive it through the full rev range. I notice in the recent Wheels Magazine that they mention that Mazda Australia recommend it should be kept below 5000 rpm for 1500 km then "thrash" it for a few hundred. On the UK RX8 site it clearly states that there is no need to follow any special process at all and that driving the car through its full range (it comes "blueprinted" from the factory) may avoid problems with sticking ports later on. Does anyone have a solidly based technical answer to justify following any of these recommendations? Personally, I drove my car reasonably conservatively but I also did a few spirited runs through the Adelaide Hills (probably revving no higher than about 6500 rpm) for the few 1000 kms. It has now done 2500 km and driving beautifully.

 

Most rotary fans regard Racing Beat quite highly, so here's their view on running in the Renesis.

 

I think 2500km you have already done what you can. I consider that you have run in. If you are as conservative as the Japanese. In their RX-8 mag, they recommended no more than 5000 rpm for the first 3000km then change oil.

I have not known any technical explanations. I would like to know too!