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?
Um. Can't find any science on this with a quick internet search. There is a product called "Stabil" that is made for long term gasoline storage. Me, I'd probably go with Stabil and not experiment w/ Argon.
A heck of a lot more than just draining the tank with a siphon (dispose of responsibly) and refilling once a year.
i would be curious to know if toyota has any instructions in the o/m, before trying something this exotic. the pip burned gas every 124 miles of ev driving, and toyota recommended filling up every 6 months. since prime doesn't, toyota must have learned something in 5 years.
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.
Just info to consider. My wife inherited a 1995 K1500 pickup when her dad passed. It sat in our driveway, untouched for about 2 years. When she was ready, we installed a new 12v battery and it fired right up. Not even a hesitation. Maybe modern gas isn't as susceptible to going stale as it was in our younger days. However, our luck didn't include the brakes. They all were locked up and needed replacement.
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.
not that i recall anyone reporting. and this has been discussed before. iirc, there is nothing in the manual.
Interesting! I’ve certainly seen the much-less-sophisticated engines of lawn mowers (etc.) stumble pretty badly on old gas; sometimes even requiring cleaning.
Buy dry ice at store. Put on gloves. Wrap in cloth. Crush with hammer. Put chunks in tank. Problem solved. Bob Wilson
The 'heavier than air' bit would only be temporary, while it remains un-mixed. It would quickly mix with the remaining air in the tank. So the main benefit would be from simply flushing out and displacing most (not all) of the oxygen. As some fuel is consumed later, oxygen will re-enter the tank and mix into all the gas (air, not liquid fuel. This is one context where American English 'gas' has too many meanings.) Next, I don't know how well sealed the fuel tank system really is, to prevent argon loss and oxygen gain. Evaporative emission controls do keep the gas exchange low, but also make use of charcoal to scrub hydrocarbons trying to escape (and to burn later). The later elements won't contribute to keeping the argon inside.
I'm pretty sure I read in the Prime owners manual that owners should burn off about 1/2 a tank minimum per six months and refill with fresh fuel. I wouldn't use "stabil" or however you spell it or "exotic" gasses. Just burn the gas and refill. No need to mess with hoaky schemes.
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.
Ping pong balls. You would need to estimate how many balls needed to form a layer, and hope that gasoline didn’t dissolve them
