Redhook98

Yep! +3 The only caveat I have about running old gas is make sure you add the additive (as a precaution) and top it off with fresh stuff. You will be fine.

FIXX

iTrader: (2)

For those that say to drain it think about this,,how long do you think our fuel sits in those big storage tanks? also have you ever saw who brings your fuel where you get your fuel from? their are tanker companies out their that deliver fuel to shell,Mobil,chitgo,speedway just to name a few,does this mean your going to drain the fuel in your vehicle because it was mixed with all those other companies fuel?

articfriends

iTrader: (1)

If your buying your fuel on the road if it is a high volume gas station the gas is usually a day or two old, I have blown stuff up on separated gas so I am more cautious than most, Smitty

stevesxm

i count 7 or 8 posts here advisng you to run it. i think they are all catgorically wrong for a couple of reasons...

1) none of these people know what kind of garbage you have in your fuel syetem

2) none of these people are going tp pay for your motor if they are wrong.

we are talking 80 bucks here. this is a no brainer. throw the stuff away and take no chances at all. none zero.

if these other guys want to take chances with their motors thats fine. you can read about it here later ...

but think about it just for a second.... enough about what is going on concerned you enough to ask the question... that was your brain telling you to be smart. be conservative.

be intellegent with your hardware.

whats going to be easier for you ? to have a good season with good motors or explain to your friends how you scrapped your motors because you were cheap ?

40gt

Or you could do the maths .....

Octane Calculator:
For example
http://www.bazellracefuels.com/Calcs/OC1.htm

Desired Octane 87 What octane do you need?
Lower Octane 80 ( assume alcohol has leeched out while standing ) What is the lowest octane you are going to mix?
Higher Octane 91 What is the highest octane you are going to mix?
Desired Gallons 75 How many gallons of mixed fuel do you need?


Low Octane Gallons 27.3 Use this amount in your mixed fuel
High Octane Gallons 47.7 Use this amount in your mixed fuel

You said you only have 20 gallons of old gas, so if you mix the two, you will end up with > 87 octane,
if the above octane assumptions are correct.

But whether you choose to go this route - as previously stated - is a personal choice, based on how accurate you believe your assumptions are and what risk level you are comfortable with.

James

With regards to the octane, I have a study with 19 different brands and octane of gasoline from 87 -93 octane unleaded pump gas. This study include leaving stored fuel in both vented and unvented 1 gallon containers. The octane was tested when new and that is 2 1/2 years go for the oldest fuel. The fuel from the pump in every case was 1 octane higher than written on the pump ( 87 was really 88 octane). Alcohol was 6-9%. After 2 1/2 years NO octane was lost, and alcohol % remained the same. The vented gas smelled bad and was slightly yellowed compared to the sealed containers. I paid $ 12,000 for this tester because I was sure my engines were blowing up due to loss of octane. No octane has been lost, I have other issues . Gasoline has many additives that will help and engine start, clean injectors clean etc........the octane test does not tell you about these additives. With regards to water in the fuel. It happens and water in the fuel is unrealted to octane, although water does have a very high octane value. Aircraft for the past 50 years purge the tanks to remove water before flight and they do not have alcohol additives. Octane boosters.....I tested 4 of them, if the little bottle says 104 octane you can bet it is, pour that 104 octane into 50 gals and you have .0000nothing for an increase in octane. The dilution is too great for an increase. Pour a shot of 80 proof whiskey in a five gallon jug filled with water then drink it and tell me when you are drunk. Just do the math to understand how much octane booster is required to raise gas not one point, but one octane.

Octane is NOT the problem, fresh gas never hurts, get the water out of the system, but blaming all the water on the alcohol is not the only problem, alcohol cleans systems which is normally good unless yours is gummed up then it is bad, alcohol is not always favorable for older fuel lines and plastics.

Alcohol adds octane so it is important but expensive additive,

Gas stations don't screw you, the guys on Capital Hill do

the mayor

I question the local stations how much of the high octane do you sell. They say we don't sell any during the winter very little in the summer. So your saying i should not worry the gas in the tank is as good as the day it was dropped off.
Ohio does not require octane checks but every state around us does so we are probably the dumping ground for weak gas.
I have used the octane boosters thinking they are good. If the bottle says it treat 20 gallons. It is not doing so????
thanks for the information

MILD THUNDER

iTrader: (3)

I suppose if a engine that is designed to run on 87 octane, is ran with a mix of last years fuel, and fresh fuel, is gonna burn up the pistons, I think the marina's, piston manufactures, and engine shops will make enough tax revenue from sales/service to balance the national budget this year.

Probably 95% of recreational boats, RV's, motorcycles and atv's will be out there running in the next couple weeks on a percentage of gasoline from october 2011 in their tanks. If pistons are gonna burn up, I better get some backup ones on order now before stock runs out.

If this guy said he had a 19ft deck boat with a 4.3 V6, everyone would tell him just run it. But because its a 525 merc, they say no way. If the engines tolerance to detonation/octane rating is the same, which it should be, why should it be any different. because the 525 costs so much? Well maybe the guy with the 19ft deck boat can't afford a new engine for his boat either.

If he said he had a supercharged high boost engine, needing 93 octane minimum to not get into detonation, then i'd say yes, drain the fuel completely, and start fresh with 93.

So, I'm agreeing with mrfixxall on this one. Fill it with fresh 91,92, 93, and take it easy for the first tank. Thats what "I" would do, and have always done the past few years. I run the boat very low on fuel in the fall, add some stabil, and fill with fresh gas come spring. Never a issue, and im supercharged. But I am not "You". If you'll sleep better at night by draining the fuel out, by all means, go for it. Its not that big a deal to do so.

James

With regards to Octane I'm saying that over a period of 2 years gasoline will not lose its Octane. It does not matter if it is Exxon station or mom & pop station the gas still maintains its octane. Aviation fuel contains low levels of lead for several reasons including Octane. The FAA does not require tanks to b e emptied annually. Each octane number is made up of 10 points. If you are adding octane booster it will help increase Octane, but it does so with huge volumes and great expense. Read the label, it will often say " add this quart of 105 octane to 20 gallons of gas" it does not say by adding this to 20 gallons you will have 105 octane. Adding quart of xyz booster to 5 gallons of gas may raise octane from 87 to 87.2 octane. Do the math, the guys selling the little bottles of booster are not lying to you, you are just reading into what you want to hear. I'll have to look at my records and give you real data on how much booster it took to raise 1 gallon one octane number.

It was written above if you have a "little" engine take the chance and if you have a big engine drain and replace with fresh. The fuel has not lost it's octane. If you trash an engine on the first outing of the year it is more likely that your A/F is off because you jetted for hot weather.

articfriends

iTrader: (1)

I have done plenty of Alchohol testing on gasoline myself after blowing up several Snowmobile engines almost immediately after filling up.
What you have negelcted to mention is PHASE SEPERATION , it is common knowledge that ethanol is hydroscopic and attracts moisture , once it seperates it WILL NOT re-mix, the danger here is running a motor and chancing getting a mixture of alchohol and water that is sitting on the bottom of the tank which would be much worse than getting some slugs of 84 octane in most cases.
Why, well we all know that stocih for ethanol is about 9.2 to one or so vs 13-1 or so when running gasoline during light cruising, as soon as a motor trys to RUN on the ethanol it is sucking from the bottom of the tank the motor goes dangerously lean EVEN AT PART THROTTLE. Hopefully when this happens the motor gets so much ethanol that it starts popping terribly and runs so bad that it gets shut off. When motors get destroyed is when a mixture of phase separated ethanol is sucked up along with enough base stock gasoline that the motor keeps running but at a dangerously lean mixture, this isn't fiction, it happens again and again every year to boaters, snowmobilers, dirtbikes etc. I have plenty of nice round aluminum ashtrays that say Wiesco as a result of it. Every spring I pump my boat gas tank dry as possible, we also know that there is pretty much no way to get every drop of old gas out of a boat gas tank unless you have the tank out of the boat so I do not fill the boat until I am ready to go out and drive it and because I have a blower motor I will mix in some race gas and like mentioned by the guys on this thread I drive the boat about as easy as I possibly can till I am sure that the gas I am running is good. I go a step further and test my gas at the pump for ethanol and water content every time I fill my boat, Smitty