so a guy in one of my classes (hvac/r tech school) works in the field already. he said that for months he was only able to afford his one set of r-410a gauges that also read r-22. he said he used them for both for months until he got a set for just r-22. i know there is a cross-contamination chance when doing that but what is the REAL amount of oil that can be contaminate to the other refrigerant. for example if you only have r-410 gauges and use them on a r-22 system.....clean the hoses good and then go to a job using r-410 should you be ok?? obviously we all know it is ideal to have more than one set of gauges but for arguments sake say you could only get your hands on one for the time being.......thanks in advance for any insight.