Oil in RX-8
 

As you all know
RX-8 uses up oil too and we have to add about one quarts every 600 miles? or so?
far as i see its different for everyone
how do we know when to add oil and how much to add??

I would just check the dipstick every couple weeks and add oil once it gets to 1/4 above the low mark.

I check the dipstick every week.!! and I would add when it's around 1/2 above the low mark.!!

I'm down to adding a quart about every 1500 miles with 29000 miles on the car(normal day to day driving). I usually have to add a quart after 6-700 miles of a long trip though (~80 mph continuous driving).