Gas level, is low bad for condensation?

The tank on a PHEV should be well sealed. There shouldn't be much, if any, air exchange between the tank and outside when gasoline isn't being added or taken out. There will always be some water in there though; it comes in with the gas. Most tanks are now plastic, and even the metal ones are better made than years ago. So rust out from condensation shouldn't be an concern. Even back then, the rust likely started on the outside.

Every little bit of weight cut will help. It just might not be something noticeable in a tank to tank comparison; too many other variables.

 

What he ^ said. Modern cars have sealed tanks to eliminate vapour pollution. No fuel vapour out, no water vapour in.

 

And if you are going to leave 1/4 tank anyway, the weight saved from full tank is only 53 lb, hardly noticeable effect on EV range IMHO.

 

If I lived in a humid climate--which I don't--I would keep the tank full. Water in gas doesn't harm just the tank, but the entire fuel system as it is pumped from the tank to the injectors...

 

i only put 4 gallons in this time, because that's all i use in 6 months. that way, i'm putting fresh fuel in twice a year.
i'm not worried about condensation, because the tank gives at half full or less 50% of the time you fill all the way up, unless you keep adding every time you get to 50%, and i've never seen that recommendation.

 

There should be just enough fresh air coming in to replace the fuel that was just burned off. That air will bring in a little bit of moisture. But without any continual air exchange (due to those modern vapor emission regulations), the total moisture supply should be small.

That may be true for folks using no-ethanol fuel. But the ethanol in the E10 that most of us get should absorb some water within the fuel system and flush it harmlessly through the combustion process. Even drivers using mostly E0 ought to have enough residual E10 for this to still happen, unless they have done a fairly thorough purge of the previous fuel.

The introduction of E10 did cause a lot of engine problems from water in the fuel, as the first E10 absorbed plenty of water that had previously accumulated for years at the bottom of various tanks in the fuel supply and distribution chain. But that was just a first-winter thing, decades ago. The continued use of E10 didn't allow that much water to accumulate again.

 

I wonder if that's partly the reason I'm getting a fair bit of water in my Oil Catch Can?

 

Water is a product of combustion. When the hydrocarbon (gasoline) is burned the carbon combines with oxygen to form carbon monoxide and carbon dioxide. The hydrogen combines with oxygen to form H2O...water. The blowby past the piston rings allows the products of combustion to enter the crankcase and eventually make their way to the catch can or just back into the intake.

 

When was the last time you heard a PSSSSSTTTTT when you loosened the gas cap ? Never ???

In addition, leaving a much smaller margin for error can mean that a small error can create a big problem.
And running it TOO low can be hard on fuel pumps.

And as was mentioned, the difference in gas consumption due to extra weight should not be measurable without special instruments......unless maybe you start and stop a LOT, like for mail delivery OR drive a lot where there are significant hills.

 

If I had a plug-in hybrid, I'd be inclined to run a fair bit of gas through, say at the least 4 full tanks per year. People drawn to plug-ins tend to be mpg junkies, and maybe that is going to shake out with engines underused, to the point that they suffer the same symptoms as vehicles that have been long-term stored?

 

toyota says to use up gas every 6 months on the pip, and runs the engine every 124 miles. but nothing on the prime, afaik. i would think there would be a warning in the o/m if it were an issue. at 6 years and 18,000 miles hv, my engine runs like new. not sure when low usage troubles might start?

 

I have cars that only get fresh gas every two years and when they come out of the garage because I need to get them pollution inspected I put fresh gas in them and drive them. I realize this is not an ideal situation it's just that I am the only driver and have too many cars.

In the winter I only insure one car, the Prius. In the summer I insure my Dodge Dakota just for the summer, I also insure my 1999 Plymouth Prowler in the summer. How many cars can one person drive?

When I am not driving a car for long periods of time I put storage insurance on them, the one that comes to mind is the Prowler is only $34 a year if I left it in storage.

My 2006 Prius was two years old when I bought it and old was the gas in it when I bought it with only 35 miles on it?

I also have two other cars that are never driven but are insured.

 

What do you do with registration? I don't think you can register a car just for a half year. Are they all registered and plated year around?

 

This is how I would approach it.

I think you're fine with those parameters for long periods of time. I don't think any issue is going to be created. However, I would approach as thinking a "long period of time" as being 6 months.

I know a lot of us, have bought or do buy Prius, PiP, and Primes, with the desire to be as "efficient" as possible, and be able to brag around the water cooler about how little gasoline we've burned.

But really? Letting your engine run enough to empty a tank functionally every 6 months is NOT going to result in Captain Planet being notified.

Whether you need to or not, or whether any harm or damage could or could NOT come with letting the gasoline sit longer, it would be worth it to me, to simply NOT have that worry, and simply very occasionally-1/2 year increments...run the gasoline low and exchange.

Yeah, the twice yearly gas exchange might screw up some sterling non-gasoline usage stats...but it would still be worth it to me. Maybe plan it around something that happens about twice yearly and is inevitable anyway, like a long summer road trip or some winter holiday driving?

Then go back to working towards the most "electric" and efficient utilization possible.

Sometimes I think we can be too uptight about burning fuel. The Prius, prime or otherwise is still a hybrid, with a gasoline engine. This isn't something you need an exorcist to remove from it's soul.

Once in a while? Burn off the mostly sitting tank..and change it. I think everything will survive nicely.

 

Yes they are all registered and plated but the ones I don't drive in the winter or very seldom I put storage insurance on them. It saves me a lot of insurance money. Indiana isn't one of the cheapest states to put license plates on cars. It can cost several hundred dollars for a new car and if it is luxury car better open your wallet. As the value of the car goes down so do the license plate cost.
My 2003 Grand Marquis it $62.35. Most of the cost is excise tax.

$270.35 for my two year old Prius

 

I take it the state accepts storage insurance for registration.