7 month old gas, what to do?

[AustinSouthSide]

A buddy of mine is buying an 03' 22V and it has had gas in the tank since August without fuel stabilizer in it. He is going to test drive it next weekend, what do you think they should do? The owner is not sure how much gas is in the tank, but it is probably over half full. Should he fill her up and see how it goes, drain the gas or something else?

[chpthril]

Add a couple bottles of Stabilizer, fill it up, and run it. May be kinda stale, but should be usable with some fresh gas and stabilizer :02:

[AustinSouthSide]

Cool, thanks for the info, I will let him know. I will also let him know to sign up on this site so I don't have to keep asking questions for him!

[dogbert]

What chpthrl says will work.

[wannabewakeboarder]

Make sure you put the highest octane in it though.

[chpthril]

Make sure you put the highest octane in it though.

No, please don't. Higher octane fuel is less volatile (takes more heat to ignite) which will compound the issue of the stale fuel. Stick with 87oct

[mtnsmith]

I don't agree with the octane statement there. I'd run it with the same gas that is already in there, if it was high octane, then ok. There was a thread some time back that took on the premium/regular gas myth. Here it is.

http://www.tigeowners.com/forum/showthread.php?t=5133&highlight=gas

[laserfish]

No, please don't. Higher octane fuel is less volatile (takes more heat to ignite) which will compound the issue of the stale fuel. Stick with 87oct

Chpthril is right! Seems like it should be the other way around but it is not. Use quality 87 octane, and you should be fine. Just be sure and use stabilizer this time.

[chpthril]

I don't agree with the octane statement there. I'd run it with the same gas that is already in there, if it was high octane, then ok. There was a thread some time back that took on the premium/regular gas myth. Here it is.

http://www.tigeowners.com/forum/showthread.php?t=5133&highlight=gas

Mine or wannabe's statement???

[mtnsmith]

Sorry, wannabe's. I hit the reply button before your post was up.

[chpthril]

Sorry, wannabe's. I hit the reply button before your post was up.

:ro: :ro: :ro: ;)

[noworries]

The problem with old gas is it turns to sticky varnish. I thought I'd burn off some old nasty smelling gas by putting it in my lawn tractor. I ended up almost seizing a valve but bending a pushrod in the process. Fortunately, I got by with just replacing the pushrod, and a new tank of gas. If the gas smells bad, get it out of there, don't even mix it, particularly if the tank's half full.

[wannabewakeboarder]

Chp,
Dosen't gas loose some of its octane after sitting for a while? So wouldn't you want to add higher octane fuel to even the octane out? Please correct me if I'm wrong haha I'd like to learn somthing.

[dogbert]

:ro: Chp,
Dosen't gas loose some of its octane after sitting for a while? So wouldn't you want to add higher octane fuel to even the octane out? Please correct me if I'm wrong haha I'd like to learn somthing.

Higher octane gas goes bad more quickly. Compound that with the fact they don't sell as much of it. It also has different ignition characteristics. You really need to stick to the octane rating recommended by the manufacturer. I can always tell when they substitute a different (higher) octane rating at the gas pumps where I get gas for my truck.

[eks]

:ro:

Higher octane gas goes bad more quickly. Compound that with the fact they don't sell as much of it. It also has different ignition characteristics. You really need to stick to the octane rating recommended by the manufacturer. I can always tell when they substitute a different (higher) octane rating at the gas pumps where I get gas for my truck.

I looked at the manual and never found the right octane, Does anyone know what is the right octane for the MP 340?

[dogbert]

My dealer recommended mid-range gas, but I've been using regular just fine.

[chpthril]

Chp,
Dosen't gas loose some of its octane after sitting for a while? So wouldn't you want to add higher octane fuel to even the octane out? Please correct me if I'm wrong haha I'd like to learn somthing.

Here is some info that I posted over on WW the other day. It may sound a little out of plasce, but it's easier then retyping.

"1st, the octane number has nothing to do with the "Quality" of the fuel. Octane represents the volatility of the fuel....how much heat it takes to ignite the air/fuel charge. 87oct is more volatile then 89, and so on.

2nd, Fuel is a ratio of Octane and Heptane molecules. It doesn't loose octane, but simply becomes less volatile over time, but still retains the same number of Octane and Heptane molecular (87oct is 13 parts Heptane, 89 is 11 parts, 91 is 9 parts). Octane handles ignition pretty good, but Heptane does not, so we control the ignition by changing the ratio of Octane to Heptane for engines of different compression ratios. More Oct, less Heptane for higher compression.

A fuel's Octane rating is about controlling Pre-ignition in the combustion chamber. The lower the Octane number, the more Heptane the fuel has, the more volatile it is, and the less heat it takes to ignite. HP is a result of compression, compression builds heat, heat ignites fuel. If the fuel ignites early, and on it's own, (pre-ignition, or "spark-knock") we don't get the full force pushing down on the piston to turn the crankshaft, which results in loss of power. To prevent the pre-ignition, we use a fuel with a higher octane number (less Heptane, more Octane) which takes more heat to ignite because it's less volatile. Once ignited, all have the same burn rate.

The EPA regulates the minimum standards on cleaning additives. All fuel grades will have the same, plus what the Oil co adds on it's own.

You WILL NOT get better fuel mileage or performance, or a cleaner engine by using a higher oct as the OIL Co's want you to believe, you are just increasing thier bottom line.

Byrd, you need to use what the engine manufacture recommends, fuel injection has nothing to do with it. The ECM doesn't now or care what fuel you are using. It uses a Knock Sensor to feel for vibration caused by pre-ignition. Once this is detected, the ECM will retard the timing and increase the fuel mixture to stop it. This has a direct and negative effect on performance and fuel mileage. Not to mention that pre-ignition it also damaging to the engine.

As stated, there is NO performance gain to using a higher Octane fuel then what your engine calls for, but only a negative. Increased cost, less mileage, increased emissions, cold drivability symptoms, more deposits left behind."

Let me know if this opens up more questions :ro:

[chpthril]

I looked at the manual and never found the right octane, Does anyone know what is the right octane for the MP 340?

87oct if you have a choice.

[Jason B]

If the tank was 1/2 full you may very well have a good amount of water from condensation also. I would replace the water/fuel seperator(sp?) as well.

Personally, I would get a vacuum pump and suck out as much fuel as humanly possible. Open the floor panel, disconnect the fuel filler hose and drain it as dry as possible. Why take the chance of mixing gas? It won't take more than 45 minutes to drain it. Do you know what a marine mechanic charges? If not you're very lucky. Suck it dry.

[chpthril]

If the tank was 1/2 full you may very well have a good amount of water from condensation also. I would replace the water/fuel seperator(sp?) as well.

Personally, I would get a vacuum pump and suck out as much fuel as humanly possible. Open the floor panel, disconnect the fuel filler hose and drain it as dry as possible. Why take the chance of mixing gas? It won't take more than 45 minutes to drain it. Do you know what a marine mechanic charges? If not you're very lucky. Suck it dry.

The hard part is finding a place to dispose of 18gals of gas.

[sparky216]

The hard part is finding a place to dispose of 18gals of gas.

That's what Bon-Fires are for:ro:

[wannabewakeboarder]

The hard part is finding a place to dispose of 18gals of gas.

It works good for killing those darn weeds that grow around my driveways and garages.:ro:

[dogbert]

It works good for killing those darn weeds that grow around my driveways and garages.:ro:

Gasoline contains many toxic additives that you don't want getting into groundwater.

[Jason B]

It works good for killing those darn weeds that grow around my driveways and garages.:ro:

Not a good idea.
I use my old gas in the lawnmower and weedeater. If I have a bunch I give it to my nieghbor also and he uses it in his mower also.
Don't pour it on the ground....bad, bad, bad.