Well, which of their products was he pushing? Full synthetic, semi-synthetic, or water-soluble oil? What materials do you run?
Sounds like you need long sump life for one thing, but other factors include your budget, materials you run, operations on that work, and disposal costs.
I've got a home-shop environment, and have a manual lathe. To say it doesn't run every day would be a gross understatement....it sits for weeks without running coolant. I'm using the Valenite ValCool VP-Tech semi-synthetic. It's fairly inexpensive (fits my budget, which is thin to say the least), and has incredible sump life. It's been in there a year and still looks like the day I put it in. I run anything that falls in the door, from aluminum to brass to steel and stainless. The VP-Tech works great on everything, and doesn't stain.