PegasusCapital

When storing the C7 for the winter, is there a factual, mechanical reason for not filling the fuel tank as much as possible in order to prevent condensation? I've seen several posts that talk about fuel sensor corrosion problems with a full fuel tank for extended periods but haven't been able to determine whether that's a real issue or not.

Zjoe6

I don't know the source but my corvette club announced that c5,c6, and c7 should only have 1/4 tank due to sulfur in the gas contaminating gas tank internals like you mentioned. I thought the source was an engineer at GM but I'm not certain. So I just stored mine and happened to have 1/4 tank left. I poured 3 ounces of star tron fuel stabilizer and drove it to the oil change and back, then parked it for the winter.

Last winter I filled it with non-ethanol gas and stored it.

The below was copied and pasted from another forum. It discusses what I mentioned above.
**************************************** ************************************
Quote: STORAGE INFORMATION from Paul Koerner, GM Master Corvette Technician.

If you plan to store your C7 for longer than one month, Paul emphasizes the following points. Review your owner's manual for more storage recommendations (battery tender, ect.).

- Store newer Generation (4 through 7) with 1/4 tank of gas.

- Use fuel stabilizer if storing for longer than one month at a time.

- Change oil before storage

The reason for only storing with 1/4 tank of gas has to do with the location of the fuel sending unit. In the C7, the fuel sending units are half way up inside each of the two tanks. Sulfur in the gasoline can coat the fuel level sensors, causing the fuel gauge to become inoperative. The reason that this does not happen when you are regularly driving the car is that movement of the gas in the tanks keeps the contacts clear. In order to clean the contacts, use a 20 ounce bottle of (Auto Zone, etc.).

The old reasons for storing with a full tank of gas no longer apply with the C7. The double sealed fuel filler neck and the charcoal canister on the other side of the tank prevent moisture build up from taking place.

Unquote
**************************************** ****************************************

Millerrock

I have stored with a full tank and not even worried about it other times. It's going to be almost 2017, it's not like back in the days. Use good fuel, I rec shell, I never have had fuel issues and since it's a fuel rec by Ferarri I think I'm good to go. I have checked with algar which is mine local ferarri dealer and they store with a full tank, add an enth remover and store it.

JerryU

FWIW. There was an interesting recent post that said not to fill more than half way to keep the fuel level sensor out of the gas! There are reports of sulfur buildup on the sender causing poor readings. Some have had dealers use two bottles of the fuel cleaner mentioned in the Owner's Manual to solve the problem. Others have had their tanks removed to replace it (very big job, requiring drive train removal as I recall.). The cleaner does say it restores fuel sender operation.

I use that GM cleaner at every oil change as recommended if not always using Top Tier gas. Apparently not as good as only using Top Tier gas but I don't always use it. I also think it may help the injectors keep clean.

In addition Top Tier has to do with cleaning additives NOT the fuel's sulfur level. That probably depends on the source of the oil the gas was refined from and just where the dinasour died!! Oil, like other products that come from the ground, varies in contaminants. Don't know how the sulfur level is controlled but it is a known cause of fuel level sensor failure.

PS: Decided to google and see who is controlling sulfur levels in gasoline. It's the EPA and not related to Top Tier. Summarizing what was found:
The EPA just reduced the level of sulfur allowed in gasoline again and is (or at least was before November 8!) determined to reduce sulfur to very low levels by 2030. The EPA said the final rule will cost $1.5 billion per year when it is fully implemented, while the annual health benefits will be $6.7 billion to $19 billion. The agency said the rule will prevent as many as 2,000 premature (that's is the correct word they are 'NOT' prevented as is often stated, they are just postponed!) deaths per year.

As many elements Sulfur that can be harmful at low exposure levels when breathed but is beneficial when ingested. Sulfur is important for its role in producing glutathione, a powerful antioxidant, and for health of your hair, skin, nails and connective tissues (like joint.)

Side Bar: OSHA is about to implement the new very low allowable breathable Manganese level in welding fumes (~4 times lower than the WW I poison gas, Phosgene) that will require production welders to essentially wear respirators similar to those used in spray painting or the equivalent performance PAPR! However it's a required element to ingest and is in many daily vitamins pills.

vettnutt

20 years of a full tank with Stabil added has never caused an issue.

cor66vette

This is good stuff, too. Emits some kind of vapor that treats the gas AND the inside of the tank not covered in gas.
https://www.goldeagle.com/product/st...60-performance

dvilin

Have always stored with a full tank no additives and no problems..

6spdC6

Well I'm old school and have been storing vehicles since 1970! I store with tank mostly full (about 7/8 of a tank) I put a good chemical in the tank.Its well mixed as I have a 25 mile ride home from the gas station.

I have had a 98, then a 05, then traded for a 07Z06 and now the 15 and FWIW 4 boats stored the same way.

Always Red Dave

Full tank but mine seems to be only out 3 months of the year lately so I don't no how much it would matter for me. If I was storing for 4 or 5 months I would go with FULL TANK!

Harry2

Same here, filled the tank up today, drove 25 miles and then put it in hibernation until April, same as my previous three other Vettes with no problems encountered.

joemessman

The recommendation is one quarter now because of corrosion to the sending unit. That is from GM. Just because you never had an issue doesn't mean it is OK. My grandpa smoked two packs of cigarettes a day and never had a problem. Live to be 101. Doesn't mean mean its OK to smoke 2 packs of cigarettes a day. He dodged the bullet.

tony abbski

I'm a big believer in Stabil, had my boat in storage both outside and in for five years after properly fogging out, and winterizing, used Stabil,for first year with full tank of gas, and added more stabilizer every year.
I was still leery when I had the mechanics go over it and put in new batteries etc. I wanted them to dump the fuel as a precaution. They didn't have the facilities to get rid off the fuel safely, said it smelled fine and started it up with no issues.
I burned the entire tank of fuel in one day with much cruising - not even a hiccup, no stalls or hesitation. I credit the proper winterization process and Stabil.
I have friends who did not use file stabilizer for one year and had to clean fuel lines, carbs etc after they got all gummed up. Not worth the hassle to not use stabilizer IMHO. I use on all my seasonal power tools and works great for them too.

PegasusCapital

When you say "That is from GM", in what form did "That" take? Has there been a TSB or other form of written communication from GM on this? Maybe an article in a Corvette magazine? I'm looking for something other than anecdotal comments.

DickieDoo

I don't understand the difference between sulphur corrossion of the sending unit between STORAGE and normal Driving. Wouldn't it be the same issue, especially for those who keep the tank relatively full all the time, the sending unit would be soaked all the time regardless.

The reason to keep you tank full while operation your vehicle is that the full fuel acts as a coolant for the fuel pump, running the car at low fuel levels is supposed to make the pump run a bit warmer and more likely to early failure.

Condensation is not such a big issue for those of us that stores our cars indoors.

I full believe that a good fuel stabilizer that is run throughout the fuel system is more important.

joemessman

I'll try to get more information on this issue, but when I read the article online a while back I copied this information from it and saved it to my Corvette documentation folder. But for now please read this and I will follow up by tracing more information.
STORAGE INFORMATION from Paul Koerner
If you plan to store your C7 for longer than one month, Paul emphasizes the following points. Review your owner's manual for more storage recommendations (battery tender, ect.).

- Store newer Generation (4 through 7) with 1/4 tank of gas per GM engineers.

- Use fuel stabilizer if storing for longer than one month at a time.

- Change oil before storage

The reason for only storing with 1/4 tank of gas has to do with the location of the fuel sending unit. In the C7, the fuel sending units are half way up inside each of the two tanks. Sulfur in the gasoline can coat the fuel level sensors, causing the fuel gauge to become inoperative. The reason that this does not happen when you are regularly driving the car is that movement of the gas in the tanks keeps the contacts clear. In order to clean the contacts, use a 20 ounce bottle of Chevron Techron Fuel System Cleaner (Auto Zone, etc.).

The old reasons for storing with a full tank of gas no longer apply with the C7. The double sealed fuel filler neck and the charcoal canister on the other side of the tank prevent moisture build up from taking place.

Formula52

I found out about this at Carlisle from one of the maintenance engineers at the show. But I am going to roll the dice and put my car away with a full tank as I have done for many years in the past without any problems....

B-STOCK

Techron fuel system cleaner proved it's worth keeping the fuel gauge sending units on the trouble prone C5s working fine. I had the problem 17 years ago in my C5 and insted of having the dealer replace the sending unit under warranty I used a bottle of Techron and it cleared the problen right up. Used a bottle a year but last year had the same problem. Used a second bottle and it's perfect again. Use the FUEL SYSTEM CLEANER not the fuel injection cleaner. Have not decided weather to use 1/4 of a tank on my C7 but never had a problem with a full tank, stabil and techron.

Bill Dearborn

When I started storing vehicles over the winter a full tank was recommended for two reasons. The first was moisture condensation inside the tank. The air in the tank has a certain amount of moisture in it and during the winter the moisture drops out of the air as the ambient air temp drops. The second was a fire issue. Supposedly, vehicles without full tanks that are in fires have a greater chance of experiencing an explosion since there is air in the tank and as the fuel gets hotter it vaporizes and has a greater tendency to explode if exposed to a spark/flame as the tank becomes compromised. A full tank pushes gasoline out of the tank which then burns without the explosion. At least that was the instruction I received when I took my Power Squadron Initial Boating Safety Course 48 years ago.

Bill

carpe dm

Ditto. I have used Sta-Bil and have usually added a little Marvel Mystery Oil as well. Has always worked well!