Gasoline

windrose · Post by **windrose** » Sat Aug 27, 2005 11:34 am

I always heard that you were to fill the tank up before putting the boat away for the winter. Last night, I was talking to a marine mechanic and he said because of the high volume of gas used over the summer the gas at the end of the season is the lowest quality of the entire year and has the highest percentage of additives. He says to try to run it as dry as possible before putting it away because the spring is the best quality of gasoline available all year.

I asked him about condensation, he said as long as there is a good filter and some fresh start in the old gas that the engine will run better because the gas is so much better in the spring.

Thoughts?

Post by **Tim** » Sat Aug 27, 2005 2:35 pm

Why not just buy gas at the gas station and jerry jug it to your boat at any time of year? Auto gas is typically fresher than the stuff at marine locations since the volume pumped is higher (which means more and fresher deliveries). Plus, the price is usually much lower, though low is a relative term these days. Going to fuel docks is a pain, and they hate sailboats because they take 10 gallons. Woo hoo.

Either way, I'd plan on that new filter in the spring anyway. Personally, I think the condensation thing is overrated, but it can't hurt to have a full tank either, for that matter. Do add stabilizer to your gas for storage.

CharlieJ · Post by **CharlieJ** » Sat Aug 27, 2005 5:43 pm

Down here, with our humidity, and wild temp swings during fall/ winter and spring time- Condensation CAN be a huge thing. A half full tank can collect a good deal of water over a winter.

As an example, several years ago we had a sleet storm on Thursday night-

Friday there was 2 1/2 inches of ice on the ground.

Saturday afternoon it was 86 degrees!!!

THAT can cause immense condensation problems, even in auto tanks.

Of course on Tehani I have a pair of 3 gallon tanks- I usually just occasionally dump them into the truck and get new gas *grin*

Figment · Post by **Figment** » Sat Aug 27, 2005 8:06 pm

Disclaimer: The following is the rant of a fledgling Cranky Old Yankee. Local conditions may vary.

Your mechanic's advice runs counter to just about everything I know about the oil/gas business.

First of all, being the first one to the gas dock in the spring is the dumbest move ever. Marinas don't just order up new gas at the beginning of the season. They sell what's left in the tank first, so that first-of-spring gas is the leftover from the previous summer. Unlike the "last tank of the year" you put in your boat in the fall, it did not get any fuel stabilizing additives mixed in, and you're getting everything that settled to the bottom of the tank all winter long pumped into your boat.
I come from a long line of powerboaters. We wait until the absolute last possible moment before visiting the fuel dock in the spring.

The thing about the late-summer gas being low quality and high in additives makes no sense to me. The additives cost the oil company a lot more than the gas does, so it would be a foolish way to bulk up a dwindling supply. Much easier to simply raise the price to meet the demand.

True, a proper fuel system will have the filtering capability to handle some condensed water, but why bother when it's so easy to avoid?

I wholeheartedly agree with Tim. Sailboats use fuel in such small volume that it's sensible to buy the fuel at the corner gas station. Much better quality and price.

Also, because we use/store so little fuel, I personally favor draining the tank completely at the end of the season. This is impractical for powerboats with hundred-gallon tanks, but siphoning ten gallons from the boat to the car is a no-brainer.

FWIW, I personally know six "marine mechanics". They're good guys. They're crappy mechanics. They can change an impeller like nobody's business, but when it comes to the finer points of the internal combustion engine they're total hacks.

windrose · Post by **windrose** » Sun Aug 28, 2005 2:48 am

I guess I should have clarified more.... he was not talking of simply the fuel dock. He was speaking of the state of fuel supply.... overall. After the summer rush on gas for vacation, etc, etc. Fuel has the very most additives in it and is the very lowest quality at this time of year..... regardless if buying it at the dock or bringing it in jerry cans? That was the point.

I give merit to the fellow who shared the info with me, he has worked for himself... as a marine mechanic for the last 23 years. He backs up his work, not some company that he endorses or endorses him. He endorses his work and himself. His opinion, I believe it has merit. Maybe, maybe not.... decide for yo self....arrrrgh!

Oh by the way, anybody seen my engineer scale? or my pocket protector?
Mostly my pocket protector.... in case things get more technical...ARGH!

Post by **Tim** » Sun Aug 28, 2005 5:51 am

windrose wrote:...he was not talking of simply the fuel dock. He was speaking of the state of fuel supply.... overall. After the summer rush on gas for vacation, etc, etc. Fuel has the very most additives in it and is the very lowest quality at this time of year.....

Somehow that doesn't really compute, but I'm not in the oil industry.

Post by **dasein668** » Sun Aug 28, 2005 8:10 am

Tim wrote:
windrose wrote:...he was not talking of simply the fuel dock. He was speaking of the state of fuel supply.... overall. After the summer rush on gas for vacation, etc, etc. Fuel has the very most additives in it and is the very lowest quality at this time of year.....
Somehow that doesn't really compute, but I'm not in the oil industry.

Well, its certainly not true for diesel... perhaps gas is different. For diesel, the worst fuel is over winter when it has stabilizers and anti-coagulants added to deal with cold weather.

heartofgold · Post by **heartofgold** » Sun Aug 28, 2005 7:16 pm

I used to work in the aviation industry and spent several years at the airport as a fuel supervisor. Avgas, which is generally 100 octane low lead was what we used in the small receprocating prop planes. It was customary to fill tanks upon arrival, for the purpose of preventing condensation in the tanks. Here on the Gulf Coast, our summer humidities are extremely high; with gas tanks in the wings which are directly exposed to sunlight all day long, condensation can be a real issue as the fuel cools overnight. We used to even top off our tanks in our fuel truck at dusk as a policy. Remember, however, that a fuel tank in a boat is quite different than that of an aircraft wing or tanker truck where the tank is exposed, almost directly, to the sun. Nestled somewhere in the bowels of a boat, the temperature change may not be as extreme, and even in higher humidtiy environments, condensation may not be as much of an issue.

On a side note, as a supervisor, I had to daily sump the trucks to verify the appearance of the fuel and inspect for moisture, which was rarely present. We were suposed to discard that sumped fuel, but who wants to "throw away" 2 gallons of gas. Ten gallons a week of 100 octane went into my gas tank. (man! that V8 ran smooth....)

windrose · Post by **windrose** » Mon Aug 29, 2005 3:39 pm

Your responses got me to wondering.... here is a report from the EPA if anyone is interested. Summer fuels have more additives to reduce emissions. They burn cleaner but not as easily as winter fuels. However, that being said.... from the report, winter fuels are also not as stable as summer fuel because of the additives in summer fuel so I guess it really comes down to how much gas one uses over a season and how hot the area you use the boat in is as to which fuel is better. However, from the information in the report, it would seem to me winter fuel would be better for spring start up adding summer fuel as the temps increased, thus not filling up the tank at summer's end.

http://www.epa.gov/otaq/regs/fuels/r01051.pdf