Sinker EDM oil recommendations

A friend of mine has an old sinker he uses fairly regularly. The oil is pretty old and is thinking the oil needs replaced. Somewhere along the line North American EDM supplies contacted him. They recently contacted him again with sale pricing on their oil.

They offer a general purpose oil, a semi synthetic, and a synthetic.

Skin irritation is a big concern. Only the synthetic notes "will not irritate ... skin"

Has anyone heard of or dealt with this company? A google search turns of nothing on PM and little elsewhere.

Sale price on 55gal of the general purpose is $618, my inclination, for as little as he burns anymore, this will suit him fine and last him the rest of his life.

I'm hesitant with the semi or full synthetic as he wouldn't have the time to do a full system clean. I've read that is a must.

Iono Plus , very little irritation, excellent burn characteristics. Pricier than what you mentioned, IMO worth it. Yes , a full system cleanout is
required. Actually I would highly recommend this with any brand he decides to use. Kinda crazy not to as any of the newer dielectrics are easily contaminated.

Another vote for Iono Plus from Oelheld.

My sinker is in my home workshop, gets used VERY rarely, but I wanted an odourless non inflammable electrolyte. I've used this in this machine for well over ten years,probably fifteen, never changed only occasional topping up and filter change.

Edm 244 from commonwealth has been my choice for many years. Hign flash point, Odorless and a price point well under Iono Plus. Only ever had to top up tanks, oil is checked every couple years and has always been good.