Is there a safe alternative to vacuum pump oil available retail most places when in a pinch? I know guys running vegetable glycerin and hydraulic pump fluid from an auto parts stores in their vac pumps, but i don’t know how safe that is even if they have been doing it for years and the pumps still churning.
Wtf no. If you need inland 19 oil I can ship it to you.
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Auto zone baby!! They have vacuup pump oil. Cheap but works
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figured. i just know a few cheap extractors who have been blasting since open blast who have used both and while i’d never do it without confirmation from someone reputable i figured it was worth asking since i forgot to order there is nothing local and now I’m low.
And dude up top is wrong. Ive used compressor oil in a pinch. Didnt really care about the pump. Pump still pulls full vac 8 years later. (Not used much its a back ups back up 2 stage harbor freight) still has the compressor oil in it from 8 years ago…
Would i do this to my spd pumps? Hell no. But in a pinch hf sells it. Auto zone has actual vac pump fluid
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Well he asked for a safe alternative, not just something that would work in a pinch.
He literally said when in a pinch. Everything i listed is safe fore use in a vac pump. Jus sayin
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Ignoring lubricity, the pump will be limited by the vapor pressure of the fluid in the pump.
I imagine the glycerin filled pump you mention is probably not capable of high vacuum, and most likely has internal rust.
let me ask you this, what do you use your pump for? If it isn’t high vacuum you may want an oil free piston pump or something better suited to the application.
Do you know how many times I had to get in the zone?! 
I would go with @Slabby suggestion 10/10 times before putting glycerin in a pump or something last ditch.
I went looking for vac pump oil locally after a vac chamber kit arrived before expected. Nothing at my local part stores, but I found a gallon of Agrimaster Vacuum Pump Oil at the local farm store. It doesn’t specify a grade, but it does say it is for use in all piston and rotary milking machine vacuum pumps. It has anti-wear and anti-foam additives, along with corrosion and oxidation protection. I figure I’ll give it a try since the pump and chamber was dirt cheap anyhow. Might not pull a super deep vac, but it’s only for vac chamber purging anyhow.