Factors like working environmental conditions, temperatures and operating power as well as the product packaging and enclosure type may need to be considered for any lubricant applications..
I would suggest to consult the product technical specifications or seek the recommendation from the equipment manufacturer for the proper lubricant..
Looks like a variac. The wiper on that will be graphite and no lubricant should be used. The spindle bearings should be sealed so no lube there either.
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