We have a great condition but old shaper and hobber machines (Barber Colman). Currently we are running small- 10" to large 20" ring gears of carbon steel. The machines have always run on cutting oil but we are trying to decide if it would be possible to switch over successfully to an emulsion type coolant or fully synthetic. We have tried the idea successfully on cast iron parts and would like to see if there is anyone out there that has made this switch or know of someone who has on hardened steel. Thanks in advance!