Two problems related to engine oil leaking have been reported for the 2005 Mazda RX8. The most recently reported issues are listed below.
Oil cooler hoses rust out at fittings and leak oil uncontrollably. One search of any Rx8 forum and you will find all years are effected.
My 2005 Rx8 continually leaked oil to the point of the engine oil light coming on. Since Rx8's consume oil in the combustion process, at first this seemed somewhat normal. After a few days of adding oil only to have the light come back on, I took my car to the dealer. The mechanic brought me out to the car to show me that the oil cooling lines had been rusted out and as he put it "were spraying oil". Aside from the fact that Mazda used parts that don't resist corrosion, this is a safety issue as the lines were literally spraying oil and had the potential to spray oil onto the wheels/brakes creating a hazardous situation. Mazda is now charging an exorbitant amount to repair something that shouldn't be occurring in the first place. This exact problem has led to a recall in canada, but Mazda claims there aren't enough occurrences in the USA. That does not sit well with owners who commonly have this problem of which there are many that I have encountered on the internet.