Aspen Fuel FAQ's

FAQ's about Aspen Alkylate Fuel

All you need to know about Aspen Alkylate Fuel

What is Aspen Fuel?

Aspen fuel has been developed as an alternative fuel to standard 'pump' petrol, for use in all small 2 stroke and 4 stroke spark ignition engines. Aspen is an 'alkylate fuel' made in a special process which produces a clean burning fuel similar in combustion properties to petrol but without the dangerous substances such as benzene and aromatic hydrocarbons. Aspen also stays fresh for many years unlike petrol which goes stale in a matter of a few months. In short, it is an 'environmental fuel'

Where is Aspen made?

The Aspen production facility is at Hindas in Sweden.

What is the the main ingredient of Aspen Fuel?

The main ingredient of Aspen fuel is Alkylate Petrol. The Alkylation process takes place at oil refineries where surplus gases from the crude oil distillation and cracking plants are mixed to form a liquid called Alkylate, the purest form of petroleum product. This Alkylate is shipped to the Hindas plant where it is mixed with a few other components to form Aspen alkylate fuel.

What makes Aspen better than petrol?

Aspen contains no benzene, sulphur or aromatic hydrocarbons. These substances can, and do, cause serious health problems including Lukaemia.

The engine also benefits from lower carbon deposits resulting in a very clean upper cylinder, exhaust and spark plug.

As Aspen contains no ethanol Aspen can be stored safely, either in the can or even in the engines fuel tank without degrading. Even after long periods with no use the engine will start easily with no problems.

And the environment benefits from the reduced emissions, for example the formation of ground -level ozone (smog) is reduced by over 50%.

Do engines operate more efficiently on Aspen?

As Aspen is much purer than petrol and contains no double bonded molecules, the 'flame front' is much smoother and therefore more efficient, so a small improvement in performance may be noticed, along with easier starting and smoother running.

Are engines more fuel efficient on Aspen?

As carburated engines feed their petrol through jets which meter volume then there is unlikely to be a significant saving in volumetric efficiency. And as most small engines work at high revs there will be no reduction in revs though slightly higher power  may be achieved with Aspen, so there is unlikely to be any significant gain in "MPG".

Does oil have to be added to form a 2 stroke mix of Aspen?

The Aspen factory has already done the work and added 2% of a very high grade "Full Range Technology" (FRT) oil to the red cans labelled as Aspen 2, for use in all two stroke machinery, including water cooled, and air cooled engines.

The blue cans contain Aspen 4 and has no added oil, so is suitable for all traditional 4 stroke engines with separate oil lubrication from the sump.

Is it true that Aspen keeps much longer than petrol?

That is correct. Aspen alkylate fuel has a life span of approximately 10 times that of regular petrol. Aspen has a storage life of 3-5 years compared to 3-5 months of regular petrol. when you choose alkylate petrol for your machines you can safely put them away over winter without emptying the tank, safely knowing that they will start without a problem come spring.

Can Aspen harm your engine?

No, quite the opposite! Aspen fuel keeps your engine cleaner and gives better running protection, better performance and a longer service life. The principle is that the cleaner the fuel, the less damage to the engine. Compared to pump fuels, alkylate petrol keeps for approximately 10 times longer and alkylate petrol can be stored for years without losing quality; you don’t have to run your machine dry before winter and it will start much easier after long periods of being stored. Many engine manufacturers now recommend that their engines only be run on alkylate petrol.

Why is Aspen more expensive than petrol?

The availability of alkylate petrol is limited. The actual alkylation process to produce Aspen is a much more advanced and expensive process which only a few refineries in the world can produce. Even if new ways of producing alkylate petrol is developed, regular petrol will still be the dominant type of motor fuel in the world. At the same time, Alkylate petrol has many added advantages apart from the health and environment benefits, these include a better performance, easier starting and last but not least the ability to be stored for years without going “stale”. The process involved in packaging and getting the 5L can from the factory in Sweden to the UK  importer in Dorset, then onwards to the local dealer before sale to the customer is also higher than the bulk supply costs of pump fuel which is delivered in much larger quantities in bulk tankers and sold through a pump!

Does Aspen absorb moisture like petrol?

No, it is the alcohol (ethanol) in petrol which is hygroscopic. Aspen contains absolutely no ethanol and so has no affinity to water.

Can I swap my machines over to Aspen with no modification needed?

There is nothing stopping you from making a switch to Aspen! If your engine is older than 15 years then we recommend that you check fuel pipes and valves in case they have dried out, been destroyed or clogged up with soot from when you have used regular petrol. It should be noted that Aspen can never do more damage to your machine because in all perspectives it is a cleaner from of petrol.

You can safely mix petrol and Aspen in the tank during the change over, but please ensure that the existing petrol is fresh. Aspen is good, but cannot revive old petrol or repair the damage that petrol may already have caused.

I have changed to Aspen but my machine does not now tickover, or pick up well


Aspen does in fact have a very slightly lower density than petrol. Whilst the difference will have no effect on WOT mixture it may just effect the engine whist running on the idle jet, especially if the the saw was already on the lower limits (a bit lean) whilst on petrol. 
So sometimes a slight tweak on the L screw is required, normally only 1/16 to 1/8 of a turn counter clockwise (richening) will do the trick. 
No need to be afraid of tweaking this screw, you can do no harm to the saw, but don't be tempted to fiddle the H screw unless you understand what you are doing. The H screw does not need touching anyway for aspen conversion.



[section headinges, that is correct. Aspen alkylate petrol has a lifespan of approximately 10 times that of regular petrol. Aspen has a storage life of 3-5 years compared to 3-5 months of regular petrol. when you choose alkylate petrol for your machines you can safely put them away over winter without emptying the tank, safely knowing that they will start without a problem come spring.