I am looking for some advice here. I came off the road when the new breed of gasses came out; I have mainly worked on R22 systems.
I remember back in those days they said you needed a different set of gauges for each of the systems, mineral and synthetic.
I am now a static engineer with 11 months to go to retirement so all my training has lapsed.
What I want to know is can you use the same set of gauges on R22, 407C & 410. I am thinking of cross contamination of oils here.

Our AC contractor only uses one set of gauges full stop, no matter what the system is. They tell me this acceptable now, is this so