graememwl
Posts: 63
Joined: Wed Jan 10, 2018 9:42 pm
Location: San Francisco Bay Area

Keeping gas fresh

Thu Feb 15, 2018 1:56 pm

The only time I have used the Rex is when I deliberately ran the batteries down below 6%. Does anyone run something like sta-bil fuel stabilizer to keep their gas "fresh"? I'm thinking I'll just code my '15 Rex to allow Maintain SoC and run the gas out every quarter to minimize "gunk" buildup in the system.
Opinions?

jadnashuanh
Posts: 5036
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Keeping gas fresh

Thu Feb 15, 2018 2:09 pm

Personally, I think it's a decent idea. But, one thing BMW did was to pressurize the tank. That helps to minimize any of the more volatile components in the gasoline from evaporating, which probably makes a difference4. So, it probably wouldn't matter, but still, to be cautious, can't hurt. An extended run would also help to redistribute the oil and clean out any condensation in parts that should help in the long term.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV
Soon (hopefully!) A 2021 X5 45e will replace the above

Benagami
Posts: 30
Joined: Thu Oct 19, 2017 5:21 am
Location: USA

Re: Keeping gas fresh

Thu Feb 15, 2018 3:41 pm

With the pressurized tank, if you put in high octane it should last at least a year. At least that's what I've read.

TOEd
Posts: 124
Joined: Sat Mar 05, 2016 5:15 am
Location: Toronto Ontario Canada

Re: Keeping gas fresh

Thu Feb 15, 2018 5:18 pm

I use fuel stabilizer in my snowmobile, snowblowers, generators, lawnmowers, outboards and i3 during the off season or if fuel won't get used for an extended period of time. In my experience fuel stabilizer helps. Less varnish in float bowls (carburetors) and less plugging of injectors (fuel injection). I am of the opinion that the i3 maintenance cycle is designed to reduce injector clogging. To read more about this issue please see https://www.injectorrx.com/clogged-fuel-injectors/

brorob
Posts: 104
Joined: Sat Oct 31, 2015 5:53 am

Re: Keeping gas fresh

Sat Feb 17, 2018 9:53 am

I would suggest running the REx every few months or so to keep the internals lubricated, as Jim pointed out and for the reasons TOEd pointed out. I think you may be asking for problems if you don't allow it to run ever so often. I always put premium fuel in mine since it's more stable but someone living in higher elevation (Colorado?) had some back firing issues when using premium fuel.

theothertom
Posts: 364
Joined: Mon Mar 20, 2017 6:08 am
Location: South Carolina

Re: Keeping gas fresh

Sat Feb 17, 2018 12:01 pm

brorob wrote:I would suggest running the REx every few months or so to keep the internals lubricated, as Jim pointed out and for the reasons TOEd pointed out. I think you may be asking for problems if you don't allow it to run ever so often. I always put premium fuel in mine since it's more stable but someone living in higher elevation (Colorado?) had some back firing issues when using premium fuel.
BMW programmed the REx to come on every so often to do what you just described. It's automatic, you don't have to do anything. At least that's how mine works.

brorob
Posts: 104
Joined: Sat Oct 31, 2015 5:53 am

Re: Keeping gas fresh

Sun Feb 18, 2018 7:58 am

theothertom wrote: BMW programmed the REx to come on every so often to do what you just described. It's automatic, you don't have to do anything. At least that's how mine works.
That's true but if the gas tank is less than 1/4 full then the maintenance cycle won't start, unless they have changed this with a recent software update. I've seen some owners state that they keep their tanks low since they don't use the REx, which is why I added my 2 cents about running it occasionally.

3Alfas
Posts: 4
Joined: Sun Apr 01, 2018 2:58 pm

Re: Keeping gas fresh

Sun Apr 01, 2018 3:01 pm

With my 2015 REX, I went 2 years without using the REX or adding gas. The maintenance cycle got the gas level to 1/2. On the next cycle, I had a bad smell and a check engine light. I took it in and the dealer said "no problem found but was I using premium gas?" I filled the tank and started using the REX.

The way I drive, I would use the REX for a few miles and arrive home. I'd get the "don't leave the car with a low charge warning" so I'd charge it. At that rate, it would take another two years to get down to say 1/4 level. I coded the "hold Soc" and was able to get the level down to 1/4 in under a year.

I obviously don't need the REX but this is my first EV. Next time....

jadnashuanh
Posts: 5036
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Keeping gas fresh

Sun Apr 01, 2018 4:20 pm

I think one reason why BMW pressurizes the gas tank is to help prevent the more volatile components of the fuel from evaporating. Yes, there's a vapor recovery system, but with long-term EV use, and no fuel use, that would get saturated. Anyway, if you're worried about it, you might try some fuel stabilizer. If you're really worried about it, you might find a place where you can buy MOGAS (unleaded, aviation fuel), but it will cost you. That has a bunch of stabilizers in it already and is alcohol free. Where I live, I can't find any car gas that doesn't have ethanol in it.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV
Soon (hopefully!) A 2021 X5 45e will replace the above

Lhs165
Posts: 2
Joined: Fri Mar 30, 2018 6:06 am

Re: Keeping gas fresh

Mon Apr 02, 2018 1:18 pm

In the US you could try. https://www.pure-gas.org/

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