I don't have proof other than using Supco zoom spout and/or 20w non detergent oil for years. Both work equally well. I use the 20w in circulator pump bearing assemblies without issue, and refilled the zoom spout with 20w. Supco works in motors with lubrication ports (something that is almost non existent now). As far as using something to ruin the motor, I have never felt the need to sabotage equipment, it can destroy itself quite fine without maintenance, which most no heat calls are generated from. You don't want a maintenance customer having no heat for a stupid reason like a fan motor failure that you maintained.