I found this information and just thought I would share. We RCer's often wonder the same thing sometimes for different reasons. I was looking for the equivalent CST rating for team associated shock oil compared to Mugen. Reason mugen oil cost $8 a bottle TA oil is $3.29 and you get more. So if you ever wondered the same thing this is what I found.
http://rcrcr.com/index.php?option=co...eral&Itemid=46