Gotta add gas every one in a while

So Toyota says regular octane gasoline is good for a year in the gen4 Prime. That's with a safety margin, and no stabilizer added. Then 5 gallons needs to be added. In practice, that is about half a tank. Then this freshened up tank of fuel is good for another year.

Japan blends in less ethanol than the US. That could mean our gas degrades faster, but I suspect it is within that safety margin.

 

The octane rating has NOTHING to do with the rate of fuel deterioration.

 

Toyota calls for regular for the Prius. That's why I stated regular.
So a tank of regular sitting in the tank for a year should not cause problems, nor need stabilizer.

 

But unless you keep filling it up or always on EV, the tank will have more and more room for air and humidity, which will mix with the ethanol, which is not good.

 

I think that is BAD advice.

Especially since most gas in the US now is E10, which tends to go "bad" a bit quicker.
I would be getting nervous after 6 months.

AND......using up a half a tank of gas every 6 months......or even every 3 months.......
really costs you little to nothing. Why take the chance ??

 

Fuel systems on PHEVs are far better sealed than on any other cars on the market, so their fuel goes stale slower. Air gets in only when the powertrain controllers allow it to. GM and the other car makers and CARB worked together to design fuels systems for these vehicles:

"... but now we've got the scoop on the gas tank used to keep liquid fuel in the Volt from evaporating or going stale for up to a year. "

How designing the Chevy Volt's sealed gas tank brought automakers, CARB together | Autoblog

 

"Up to a year".......but maybe less !!!

 

... or more, based on the experiences of numerous PHEV drivers here. Without known adverse consequences being posted.

 

Ethanol was a known quantity while these PHEVs were being developed. If you live in a humid climate, add some HEET. Though hydrous ethanol blends are less damaging to aluminum parts.

 

Since they started adding 10% ethanol to gas, no more water logged gas tanks for me. I had it happen a long time ago after filling my 36 gal van gas tank. Not one problem since about 1980 I think it was? I want the ethanol in my gas. I bought the Prime in May and it had like 3/4 tank. Now it is at 1/4 and I made a 330 mile trip plus maybe 50 more. I did charge on each end so it wasn’t that great mpg on gas. Maybe a little over 50, don’t care much anymore as gas cost now is almost nothing for a year. Next month I will put 6 gals in to make another trip. Otherwise the gas is in there a long long time. I mean I am not selling the car, and I know it one of the very best on gas, so if I know exactly or don know it is just for fun of trying to get more mpg.

 

Water is polar, and gasoline non-polar; like oil and vinegar. So water in straight gas becomes a problem for fuel systems. The isopropanol and methanol in dry gas additives have polar and non-polar ends, and will dissovle the water into the gas to caryy it out of the system.

It's the same with ethanol, but it is also hygroscopic. Roughly translated that is humidity loving, which means the compound will draw moisture out of the air. Pure ethanol soon isn't when exposed to air, and the E10 being pumped into your tank is already carrying water with it. If more water gets into the fuel, phase separation can occur. Then the water and ethanol portion separates from gas for the same effect as water in straight gas.

If that happens, adding more alcohol will get the fluids to mix again. So for the ease of mind of those in humid and wet climes, they can add some dry gas.

PHEVs require a shift in thinking about fuel consumption from trips to over periods of time, like a week or month. A PHEV that doesn't reach Prius numbers can still mean a sizeable reduction in gasoline use if the EV range covers most of their daily use.

 

I'm not hoping to change any minds with this one, nor would I want the following to be regarded as advice. I'm just giving a brief summary of my experience with two primes in the household.

The older prime is now well over 5 years old and so far has been driven almost exclusively in EV mode with the occasional forced drive (1-2 times a year) outside the city limits in HV mode just to use some of the gas now and then. Yes, the engine rarely starts even during the colder winter months. While the dealer tank lasted for 2+ years with a bottle of stabilizer, I've been since then keeping the tank with no more than 10 liters (~200-250 km) of premium Shell gas (0% ethanol) gas in it.

When I purchased the newer prime (2020) I made a point of asking the dealer to not fill it up with gas. Instead have it delivered fully charged. For the 2023 prime I ordered earlier this year, again, I asked the dealer to have it ready for delivery with no gas added.

To each their own, but this appears to be the sweet spot for me and my driving requirements. So far both cars have been operating flawlessly without a single hiccup


Cheers

ms

 

You're sure that Shell still has gas without ethanol? From what I read last week, all their fuel now has ethanol. Only Esso still has gas without ethanol, but somehow, that's not at every station, so you have to look at the pump itself.

 

Good point.

Yes, the pump said so... and so did my test kit.

 

Good to know. I'll check my local Shell station. What do you use for test kit? What I have seen in a Project Farm video is by simply mixing a known quantity of water to a known quantity of fuel, once it settles, the increase of "water" level is the ethanol that has "bounded" to the water instead of the gas. Pretty simple but effective method.

Oh, and if you drain the water from a tap at the bottom of the container, you then have an ethanol free gas Just use a gas with the highest octane level since removing the ethanol will drop its octane level.

 

Don't want to hijack this tread; but what about oil changes and how often are you EV-only people running the motor. The motor oil is also hydroscopic - running the motor up to operating temperatures is a good way of drying it out. This will also prevent internal components from rusting out. Once rust starts forming, it's going to wear much faster than a fully operational engine.

IMHO; the motor should be ran every two weeks for at least 50 miles; that'll force moisture and unburned fuel out of your motor oil. Keeping everything lubed and operating properly. You'll also find out if mice has been chewing on your wires or nesting in your car. Heating everything up, is a good thing.

Just my 2 cents.

 

This must be a Canadian thing.
In the US, almost ALL stations have E0 fuel available regardless of brand.

 

There is a risk that keeping the tank mostly empty will lead to humidity in the head space condensing out, and getting in the fuel.

You also now have gasoline contaminated ethanol and water to deal with.