Argon

My sister, a welder, had a curious suggestion for me: Periodically blow argon into my Prius Prime gas tank!

Background: Except in the fairly rare cases when I need to take a road trip, I drive well over 90% electric. I take it to a gas station about once every three months at which time I put in a couple gallons. Conceptually, I could fill it up, but as rarely as I drive on gas, that gas would sit in the tank for ... like a year and a quarter. It would get pretty stale, unless the P.Prime’s computer forces a sacrificial burn, which wouldn’t surprise me.

Broadly speaking, petroleum liquids tend to chemically degrade, mostly, by thermal breakdown and oxidation. Thermal breakdown is minor concern for gas within a gas tank (unlike motor oil in a hot crankcase), but a certain amount of oxidation is bound to happen.

So my sister’s suggestion is to fill the 9ish gallons of air in the gas tank with argon. Argon, being somewhat heavier than air, would prevent the gasoline contacting oxygen, thereby cutting down oxidation a bit. That, much like its use in MIG welding. Plus, of course argon is almost completely chemically inert.

A curious suggestion, I thought...

Anybody tried anything like that?

 

Yeah, good question. Not sure how small and cheap a tank of argon a welding shop will sell you...

 

No need to drain the tank, since I only put in a couple gallons every 3ish months. So, her thinking is that it might further reduce oxidation in that 3-month period.

My immediate guess would be that it wouldn’t help much, but maybe some.

 

Stabil or similar can reduce MPG, as I recall.

The argon strikes me as an interesting thought, but I too am inclined to guess that it’s not worth it.

 

And I’m already way below that at two gallons in once every 3ish months.

 

Ah, I didn’t fully absorb that statement until I re-read it just now. Interesting that they’d base a sacrificial burn upon miles rather than time; I’m *guessing* the Prime has such a time-based (so and so number of months since the last time gas has was added), but I don’t know that for sure.

 

Interesting! I’ve certainly seen the much-less-sophisticated engines of lawn mowers (etc.) stumble pretty badly on old gas; sometimes even requiring cleaning.

 

Ah, yes, that’s an excellent point: it would not stay striated for long. For the purposes of MIG welding, it only has to blow air out of the way, in essence.

I was thinking back to the Mythbusters investigating the “invisible water” myth: Wherein they floated an aluminum-foil boat full of air on a fish tank of sulfer-hexafluoride. Those two gases probably eventually mixed too.

 

But yes, that’s the entire goal: getting oxygen out of the tank to reduce oxidation of the rarely used fuel.

There wouldn’t be very much air to mix with. I’d put in 2 gallons of gas and 9 gallons of argon. Over three months then, not quite two gallons of air would get in there (assuming no argon leaks out, as you pointed out). Maybe once a year I’d blow in more argon, presumably after my Holiday-Season road trips.