Mazda RX 8 engine oil question

[steve1]

Need to do an oil change on a 56 plate rx8, the higher horse power model, ( if that makes any difference ), trouble is, I've been getting conflicting stories about what type/grade of engine oil to use.
One says that a tech. bulletin was issued around 06/07 actuating that a 10W/30 mineral oil was to be used, but my local motor factors are saying that according to there tech. details the right oil is 0W/30 fully synthetic.
Any one know for sure the correct oil.
Also, how much oil is left in the oil coolers, and the best way of changing this at the same time, as I understand that a valve shuts off and doesn't allow any oil out of the coolers once the engine is switched off, ( of course I stand to be corrected ).
Thanx.

[steve1]

Forgot to add, the car does not get tracked, but might get the odd hard days driving, does the same oil still apply?
Also, I believe there is an oil breather some where that can become blocked, is there any particular way of cleaning this out.

[steve1]

Just to update this, have spoken to a company called Hayward Rotary in Newbury, and they have said either, 10W/40 mineral or 15W/40 mineral, and to change every 6K miles.

[steve1]

Explain to me a bit more about the premix that people are running.