I am not so sure about what additives there are in engine oil. One can get good quality SAE 20 machine oil at many hardware stores. 3-in-one puts it up in a blue can (red can is something else). Also as Kano Microil, very highly refined petroleum based oil, wax free, and does not gum. Most of these blower bearings are so called "life time lubricated" meaning it works until it doesn't. They are made from sintered bronze with oil held in the spongy metal. You can't really re-lubricate them in any easy way but they will hold oil for a reasonable time.
Hewlett-Packard used blowers with a rubber seal at one end. They could be re-lubricated using a syringe to poke through the seal and inject some oil. I have no idea if the Tek blowers are similar. Unfortunately, once the bearings run dry they will become galled and run rough despite having new lubricant.
I agree with you that mixing silicon oil or grease with petroleum lubricant is not a good idea.

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Richard Knoppow
dickburk@ix.netcom.com
WB6KBL