The mechanic has noticed a recent uplift
in questions and concerns surrounding the
upcoming introduction of E10 fuels. The
following is information provided by the
Federation of British Historic Vehicles Clubs
that we hope members will find useful.
Federation of British Historic Vehicles
Clubs – Introduction of E10 petrol
After an extensive consultation process, the
Department for Transport has announced that they
will legislate to introduce E10 petrol as the standard
95-octane petrol grade by 1 September 2021. They
will also require the higher-octane 97+ ‘Super’ grades
to remain E5 to provide protection for owners of
older vehicles. This product will be designated as the
‘Protection’ grade.
The introduction of the 95-octane E10 grade and the
maintenance of the Super E5 protection grade will be
reviewed by the Government after 5 years to ensure
they remain appropriate to the needs of the market:
In relation to the E5 protection grade, such a review
will examine market developments over the period.
HM Government have sought to reassure FBHVC
members and historic vehicle owners that, without
a suitable alternative becoming available, it is highly
likely the Super E5 protection grade would continue
to be available.
Filling stations that stock 2 grades of petrol and
supply at least one million litres of fuel in total each
year will need to ensure one product is the Super E5
protection grade. While not all filling stations meet
these criteria, almost all towns across the UK will have
a filling station that supplies the ‘Super’ grade and
currently one major retailer, a national supermarket
group, has committed to offer the product. The main
exception to this is in certain parts of the Highlands,
north and west coast of Scotland, which will be
covered by an exemption process and allowed to
continue to market the 95-octane E5 grade.
The Federation therefore recommends that all
vehicles produced before 2000 and some vehicles
from the early 2000s that are considered noncompatible with E10 – should use the Super E5
Protection grade where the Ethanol content is limited
to a maximum of 5%. To check compatibility of
vehicles produced since 2000, we recommend using
the new online E10 compatibility checker: https://
www.gov.uk/check-vehicle-e10-petrol .
It should be noted that some Super E5 Protection
grade products do not contain Ethanol as the E5
designation is for fuels containing up to 5% Ethanol.
Similarly E10 petrol can contain between 5.5%
and 10% ethanol by volume. Product availability
varies by manufacturer and geographical location
and enthusiasts should check the situation in their
location.
Latest News:
The federation’s fuels specialist Nigel Elliott has
received some new questions with regards to
ethanol and the use of E10 in historic vehicles and his
thoughts are as follows:
There are three key areas of concern with Ethanol
compatibility with historic and classic vehicle fuel
systems:
‹ Corrosion of metal components
‹ Elastomer compatibility – swelling, shrinking and
cracking of elastomers (seals and flexible pipes)
and other unsuitable gasket materials
‹ Air/fuel ratio enleanment
Corrosion of metal component
Ethanol has increased acidity, conductivity and
inorganic chloride content when compared to
conventional petrol which can cause corrosion
and tarnishing of metal components under certain
conditions. These characteristics are controlled in the
ethanol used to blend E5 and E10 European and UK
petrol by the ethanol fuel specification BS EN15376 in
order to help limit corrosion.
Corrosion inhibitor additives can be very effective
in controlling ethanol derived corrosion and are
recommended to be added to ethanol in the
BS EN15376 standard. It is not clear if corrosion
inhibitors are universally added to ethanol for E5
and E10 blending so as an additional precaution it is
recommended that aftermarket corrosion inhibitor
additives are added to E5 and E10 petrol.
These aftermarket ethanol corrosion inhibitor
additives often called ethanol compatibility
additives are usually combined with a metallic
valve recession additive (VSR) and sometimes an
octane booster and have been found to provide
good protection against metal corrosion in
historic and classic vehicle fuel systems.
Elastomer compatibility
As the ethanol molecule is smaller and more polar
than conventional petrol components, there is
a lower energy barrier for ethanol to diffuse into
elastomer materials. When exposed to petrol/ethanol
blends these materials will swell and soften, resulting
in a weakening of the elastomer structure. On drying
out they can shrink and crack resulting in fuel leaks.
Some aftermarket ethanol compatibility additives
claim complete protection for operating historic and
classic vehicles on E10 petrol. The FBHVC is not aware
of, or has tested any additives that claim complete
fuel system protection with respect to elastomer and
gasket materials for use with E10 petrol. The FBHVC
therefore recommends that elastomer and gasket
materials are replaced with ethanol compatible
materials before operation on E10 petrol.
Air/fuel ratio enleanment
Ethanol contains approximately 35% oxygen by
weight and will therefore result in fuel mixture
enleanment when blended into petrol. Petrol
containing 10% ethanol for example, would
result in a mixture-leaning effect equivalent to
approximately 2.6%, which may be felt as a power
loss, driveability issues (hesitations, flat spots, stalling),
but also could contribute to slightly hotter running.
Adjusting mixture strength (enrichment) to counter
this problem is advised to maintain performance,
driveability and protect the engine from overheating
and knock at high loads.
Modern 3-way catalyst equipped vehicles do not
require mixture adjustment to operate on E10 petrol
because they are equipped with oxygen (lambda)
sensors that detect lean operation and the engine
management system automatically corrects the fuel
mixture for optimum catalyst and vehicle operation.
Operating classic and historic
vehicles on E10 petrol
If you should decide to make the necessary vehicle
fuel system modifications together with the addition
of an aftermarket additive to operate your classic or
historic vehicle on E10 petrol. The FBHVC strongly
recommends that you regularly check the condition
of the vehicle fuel system for elastomer and gasket
material deterioration and metallic components such
as fuel tanks, fuel lines and carburettors for corrosion.
Some plastic components such as carburettor floats
and fuel filter housings may be become discoloured
over time. Plastic carburettor float buoyancy can also
be affected by ethanol and carburettors should be
checked to ensure that float levels are not adversely
affected causing flooding and fuel leaks.
Ethanol is a good solvent and can remove historic
fuel system deposits from fuel tanks and lines and
it is advisable to check fuel filters regularly after the
switch to E10 petrol as they may become blocked
or restricted. If your vehicle is to be laid up for an
extended period of time, it is recommended that the
E10 petrol be replaced with ethanol free petrol which
is available from some fuel suppliers. Do not leave
fuel systems dry, as this can result corrosion and the
shrinking and cracking of elastomers and gaskets as
they dry out