To empty the fuel or leave it full...?

[porky]

Just leave enough petrol to cover the pick up and then fill up with fresh fuel next time you use it. Always worked for me.

[Haironyourchest]

The potential problem with that is .....The coating put on the rubber components ( carb diaphragm , impulse line etc etc ) to keep them supple is attacked and eventually removed by the pump fuel . The pump fuel its self then keeps the rubber supple for a few years . Aspen does not remove the coating but if it already been removed by the pump fuel it may then start to give problems Pershing and caking . . If you use Aspen from the get go not a problem. I changed all th rubber components in my saws when I switched over to Aspen .

 

Hmmmm....interesting.

 

If the coating is stripped would the aspen not keep the rubber supple, or does it have to be pump fuel? If so, better just keep them full of pump fuel. But I would have thought the newer saws rubber components would be way better than the stuff of years gone by. They supposed to be ethanol resistant anyway, which as I hear it is what is causing the problems.

 

We did have rot in the fuel line of a couple of saws once, but they were going on fifteen years old...

[Stubby]

Hmmmm....interesting.

 

If the coating is stripped would the aspen not keep the rubber supple, or does it have to be pump fuel? If so, better just keep them full of pump fuel. But I would have thought the newer saws rubber components would be way better than the stuff of years gone by. They supposed to be ethanol resistant anyway, which as I hear it is what is causing the problems.

 

We did have rot in the fuel line of a couple of saws once, but they were going on fifteen years old...

 

Aspen wont keep the rubber supple if the coating has been removed by pump fuel , conversely it wont remove the coating if used from day one .

[Haironyourchest]

Aspen wont keep the rubber supple if the coating has been removed by pump fuel , conversely it wont remove the coating if used from day one .

 

Well Stubby, that's really upsetting to hear....Im going to have to obsess about it for a several days now, and compulsively search for evidence to the contrary to make myself feel better. I shall most probably walk to the toilet several times this evening to stare at my saws (keep em in the lavatory for security, shed security is nil) and visualise the fuel lines cracking. Thanks.....

[GardenKit]

An interesting debate, and one that I find of particular interest.

Even before I became aware of Aspen i did not subscribe to the idea of draining carburettors as I had seen too much damage in dry stored carburettors. I always preferred machines to be stored with fuel in them, but was aware that the fuel needed to be fresh.

 

As Stubby says, pump petrol will leach out the chemicals that are added to rubber to keep it supply (actually not a 'coating' but throughout the material) Without these additives rubber components quickly perish (harden and crack). Poor quality rubbers suffer more than more expensive compounds.

 

So, 35% of petrol is solvents, which not only leach out the additives, but also soften the rubber as they slowly dissolve it (put petrol on a balloon to see how quickly it dissolves rubber). Remove the petrol, and the rubber hardens and cracks. They do not always rehydrate when new petrol is added, and cracks do not heal (try soaking a ballon in petrol, dry it and try to blow it up). A hard or cracked metering diaphragm will seriously effect the performance of an engine.

 

Fresh petrol will still slowly dissolve rubber components, but will keep it supple until such time as it becomes too soft to work. Stale petrol accelerates the rate of decomposition.

 

I know that the rubber in hoses and diaphragms is pretty hardy stuff, so all but the cheapest will survive many years whichever storage method you choose, but rest assured, they will fail at some time under the ravages of petrol, especially old petrol. Hence the stories of "I have done this for years with no trouble" but there are more stories to be told of saws that have failed due to this.

 

And of course, petrol, as it ages forms gums and other solids which line the innards of the carb, blocking jets and fuel passages, as well as absorbing moisture from the atmosphere which can cause rusting in the carb as well as forming 'gels' from phase separation.

 

Just one of the many bonuses of using Aspen is that it contains NO solvents and so will not effect rubber if used from new, but if used to follow petrol it can still allow the damaged rubber to crack following the damage initiated by petrol. So older machines being changed over to Aspen may need new rubber parts at some time in the future, but should never need them again.

 

No solids will be formed from Aspen and it can be left in a fuel system for many years as it is chemically stable and does not 'go off'

[njm]

I put a fresh mix of Stihl HP Super in my New Efco blower , left it for 3 weeks and the fuel was RED ! the fuel was leaching the colour from the machines tank

Running Aspen now

[Haironyourchest]

From the Daetwyler Rubber site (they make the rubber for Stihl)

 

Stihl relies on expertise from Daetwyler Rubber

For more than a quarter of a century, Stihl has relied on moulded rubber parts from Daetwyler Rubber.

The products of the world’s leading chainsaw maker deliver high performance, even under extreme oper- ating conditions. This places tough demands on the components used in them and means that the mani- folds and hoses made by Daetwyler Rubber must be resistant to all sorts of chemicals like oil and fuel. At the same time, they are exposed to high mechanical stress and a wide range of temperatures. “Daetwyler Rubber offers all the materials and engineering ex- pertise needed to develop and produce these complex moulded rubber parts”, says Klaus Baumbach, Head of Purchasing at Stihl. In recognition of Daetwyler Rubber’s expertise and quality, together with its reli- ability and flexibility, Stihl has named the international rubber specialist Supplier of the Year three times. And not long ago, Daetwyler Rubber was the first com- pany ever to win this award two years in a row.

 

From the "Stihl USA" site

 

 "To ensure that any remaining ethanol is removed from your equipment, STIHL recommends adding a small amount of STIHL MotoMix® premixed fuel to the tank and running the engine for a few minutes to circulate the fuel through the carburetor. This will flush any of the original gasoline out of the system and protect the fuel system components from water absorption and fuel decomposition. If the machine is going to be stored for several months, it is good practice to empty the STIHL MotoMix® from the machine’s tank, then start the engine and run at idle (do not rev up the engine) until the machine runs out of fuel."

 

So Im not worrying too much anymore...

[Stubby]

From the Daetwyler Rubber site (they make the rubber for Stihl)

 

Stihl relies on expertise from Daetwyler Rubber

For more than a quarter of a century, Stihl has relied on moulded rubber parts from Daetwyler Rubber.

The products of the world’s leading chainsaw maker deliver high performance, even under extreme oper- ating conditions. This places tough demands on the components used in them and means that the mani- folds and hoses made by Daetwyler Rubber must be resistant to all sorts of chemicals like oil and fuel. At the same time, they are exposed to high mechanical stress and a wide range of temperatures. “Daetwyler Rubber offers all the materials and engineering ex- pertise needed to develop and produce these complex moulded rubber parts”, says Klaus Baumbach, Head of Purchasing at Stihl. In recognition of Daetwyler Rubber’s expertise and quality, together with its reli- ability and flexibility, Stihl has named the international rubber specialist Supplier of the Year three times. And not long ago, Daetwyler Rubber was the first com- pany ever to win this award two years in a row.

 

From the "Stihl USA" site

 

 "To ensure that any remaining ethanol is removed from your equipment, STIHL recommends adding a small amount of STIHL MotoMix® premixed fuel to the tank and running the engine for a few minutes to circulate the fuel through the carburetor. This will flush any of the original gasoline out of the system and protect the fuel system components from water absorption and fuel decomposition. If the machine is going to be stored for several months, it is good practice to empty the STIHL MotoMix® from the machine’s tank, then start the engine and run at idle (do not rev up the engine) until the machine runs out of fuel."

 

So Im not worrying too much anymore...

 

Phew ! that's ok then ......

[GardenKit]

From the Daetwyler Rubber site (they make the rubber for Stihl)

 

Stihl relies on expertise from Daetwyler Rubber

For more than a quarter of a century, Stihl has relied on moulded rubber parts from Daetwyler Rubber.

The products of the world’s leading chainsaw maker deliver high performance, even under extreme oper- ating conditions. This places tough demands on the components used in them and means that the mani- folds and hoses made by Daetwyler Rubber must be resistant to all sorts of chemicals like oil and fuel. At the same time, they are exposed to high mechanical stress and a wide range of temperatures. “Daetwyler Rubber offers all the materials and engineering ex- pertise needed to develop and produce these complex moulded rubber parts”, says Klaus Baumbach, Head of Purchasing at Stihl. In recognition of Daetwyler Rubber’s expertise and quality, together with its reli- ability and flexibility, Stihl has named the international rubber specialist Supplier of the Year three times. And not long ago, Daetwyler Rubber was the first com- pany ever to win this award two years in a row.

 

From the "Stihl USA" site

 

 "To ensure that any remaining ethanol is removed from your equipment, STIHL recommends adding a small amount of STIHL MotoMix® premixed fuel to the tank and running the engine for a few minutes to circulate the fuel through the carburetor. This will flush any of the original gasoline out of the system and protect the fuel system components from water absorption and fuel decomposition. If the machine is going to be stored for several months, it is good practice to empty the STIHL MotoMix® from the machine’s tank, then start the engine and run at idle (do not rev up the engine) until the machine runs out of fuel."

 

So Im not worrying too much anymore...

An excellent and informative bit of research, but although the new green fuel hose from Stihl is probably the best I have seen, there are still a lot of hoses around that are not too good and will be effected by petrol solvents. It is the nature of rubber to be effected so, and even the best are not perfect.

A lot of the cheaper Chinese machines around have hoses that rot right out in the first 12 months.

And of course its not just hoses, but also diaphragms that suffer. I see failures of hoses and diaphragms on a daily basis. Believe me, it does happen.

 

Its interesting to see the Stihl comment about flushing petrol with Motomix (very similar to Aspen). They are obviously concerned about storing with petrol residue and want it washed out. I was a bit surprised to see them then recommend to tip the Motomix out. I would be more than happy to leave Aspen in.

 

But at the end of the day we all have different habits, and different understanding of the issues, so 'Out or In' is really down to what suits each person best.

[mikerecike]

I have no knowledge of chemistry but am with Barrie here. Get the diaphragms out of a dry stored 2 stroke carb and they often feel like cardboard - all elasticity gone. I've tried re- soaking them in oil, petrol, even dot 4 break fluid which somebody told me. Once that elasticity goes it don't come back.