Oil brand recommendations are as varied as there are FC3S owners - ask a different FC3S owner and you can get a different answer.  Stick with quality, name-brand oil and you cannot go wrong.  Castrol GTX (20W50) is recommended by Mazda for their reman motors.  It is more important to stick with a religious 3,000 mile oil change schedule than debating which motor oil brand is better.

For turbos, it is recommended to stick with 20W50.  If you want to use a lighter weight oil, you can use 10W30, but for those who run their cars hard, 20W50 is recommended for better oil protection due to being thicker.  It is not recommended to use 10W40 weight.  For a full explanation why, check out the Oil FAQ for further details.

As for synthetics, there are conflicting arguments for their use.  Yes, they give better protection, especially for turbo engines, but due to the oil-burning nature of the rotary engine, it is not recommended for street use.  We've found that synthetic oils produce higher amounts of deposits on the rotor housings, especially right around the spark plug holes.  For this reason, using good, quality mineral oil with 3,000 mile oil changes give more than enough protection for your FC3S on the street.

For those who have eliminated the stock oil injection system and pre-mixing, we wholeheartedly endorse using synthetics - very little is burned in the combustion chambers.
Click here for the Internet Oil FAQ!

Questions?  Comments?  Send mail to:  reted@fc3spro.com