I mentioned to a friend (who knows cars) that with my hybrid, I have not been to a gas station in 6 months. He told me that gas deteriorates after 3-6 months and can foul-up your engine.

He suggested using up the gas in my tank and after refueling, to use a gas stabilizer such as Sta-Bil.

Anyone know of this ?

 

Well, it also depends on how old the gas was in the gas station before you put it in the vehicle, from refinery to reaching the gas station to reaching your vehicle, it can be a span of a month or more. Then there is also how often the octane you fuel up is being used by other customers in the station so that also affects how old the fuel is.

Gas with ethanol expires quicker than pure gas, ethanol might become water. Water is incompressible so it might have the potential to damage your engine. It is not as bad as hydro-lock but there might still be damages.

 

You could probably get by with using non-ethanol gasoline. In Florida it is usually 90 octane. That is probably close enough to the minimum 91 octane to not cause a problem.

 

If you think your gasoline might sit around for a while, using a fuel stabilizer is a good idea. Sta-Bil or other similar brands can keep your gas fresh for up to 12-24 months.

 

if you are worried an easy solution is to add in some Seafoam to your gas tank every fill up.

I have been using Seafoam in my small engine gas containers for years now and never have gas related issues. I have filled my 2 gallon gas container before winter getting ready to use it in my snow blower and turned out we got zero snow so never used it. I ended up using that same 2 gallons of gas through spring into summer in my lawn mower and pressure washer and they start right up and run great. the gas still looked and smelled fresh. I mix 1 oz Seafoam per gallon of gas.

Not sure id be so worried about gas going bad in a modern car gas tank though since its a sealed system. Not alot of air getting into it.

Quick story about bad gas. I was at my Local Lowes last year and they had two Craftsman pressure washers set up right outside next to the snow blowers, it was the end of fall sometime. Both looked brand new and had hand written signs saying $25 each for parts only. I asked what the deal was with them, was told they were customer returns and it would cost more money to fix them than they sell for. i bought them both, figured even if i part them out I cant loose money. The hoses and wands are worth that alone. Got them home and opened the gas tanks and there was a horrid smell. Ended up draining and flushing the gas tanks, removed and cleaned the carbs and they ran brand new again. Cost me nothing to fix, didnt even change the plugs. The gas was dark brown like varnish. Im guessing people bought them in summer, used them then put them away with gas still in the tanks. Few months later they go to start and nothing due to bad gas and clogged carbs. Plus with it being a pressure washer all the water in the air must get in the gas tanks and carb. I sold one for $140 and kept the other.

I keep gas with Seafoam in the pressure washer and never have any issues. Starts first pull.

 

It's rare for the gas to become "bad" to a point it's damaging to run in 3-6 months but it does go bad. In my 4-stroke snowmobiles, it can sit for 9-10 months with no issues. If you skip a season and forget to drain it, that's where the problems start...

Long story short, fill up 1/2 of the tank and just use it every 3-6 months or so. It really is your simplest option and no additive is needed.

 

Ethanol free premium could be hard to come by in certain areas. General rule of thumb is 3 months for fuel with ethanol and 6 months for pure gasoline. Of course the figures will vary (I had an old motorcycle in storage for 6 years with gasoline that ran without issue).

Considering the value of your car is far more than a lawnmower or an old motorcycle. Just to be safe and add an extra layer of protection from ethanol breakdown, throw in a few ounces of stabil keeping 1/4 or 1/2 of fuel in the tank. Try to schedule a cycling out of the fuel in your tank every three months repeating the cycle.

 

What I heard is, half a tank sounds like a good idea on paper but there are some drawbacks. Condensation and the fuel pump uses fuel to cool it down, filling up half a tank makes the fuel pump work harder and with less fuel to cool it down it runs hotter too might fail quicker.

 

Wanted to bring this topic up again because wondering how people does it with their PHEV vehicles especially if they only use up a tank in a few months? Like for those who commute short distances like to work and always charge both ways or that the range is enough for their intended purposes. Do you add sta-bil or sta-bil 360, just curious.

 

I previously had a BMW X5 45e (PHEV). These are normally designed with pressurized fuel tanks and specify premium fuel (ideally ethanol free) that should be stable for a longer period. For instance, in the X5 you had to press a button to de-pressurize the tank and wait a few seconds before you could loosen the fuel cap. Regular X5s don’t do that.

The X5 manual had an entry that specified the gas engine would be triggered under certain conditions - time between accessing the fuel tank was one of them. Temperature was another.

Basically - my assumption is MB engineers aren’t that far from BMW engineers on reinforcing the engine (the B58 in the X5 PHEV has key differences from the 40i) and designing a fuel system that can safely keep fuel for extended periods. After a certain amount of time without the gas engine running, it will likely cycle on just because it’s programmed to do that.

 

^^I have a 4xe Grand Cherokee and it also has a pressurized fuel tank. I don’t think the GC would let me keep the same tank for 6 months. It’s always forcing fuel oil refresh mode on me where it harshly runs the engine until whatever parameters are met that it needs.

 

I see, appreciate the insight.

 

I also used to have X5 45e as it was mentioned earlier with the tank being pressurized is how system protects the engine. GLE450e gas tank is also opens after a slight delay and it appears that the same future in place. Im sure MB had it in mind
that with 50 electric driving range the car will mot be refueling a lot.

 

Beautiful, that is what I want to hear, thanks.

 

wrong thread

 

Add me to the list that used to have an X5 45e. I now have an E53 and its tank is also pressurized.

 

The Chevy Volt used to run the gas engine periodically on its own to prevent deterioration. Surprised MB does do that.

 

I would think the entire tank, or at least a good percentage of it, would have to be used - not just a quart or two.
I don't see an answer, except for the constant positive pressure that's maintained, which will reduce/prevent evaporation of volatile compounds and keep moisture out.
I use Marvel Mystery Oil in my yard equipment now, instead of Stabil. Spring startups seem easier.

 

I have a 2024 GLE 450e. Usually every week or so the ICE will kick on for a short time (1 min) when in E mode, usually when backing out of garage or parking space. I always assumed MB did this on purpose to ensure the ICE got a little work.