Ever wondered if petrol has a shelf life? Well, it does, and it may not sit on the shelf as long you think.
In fact, petrol starts degrading from the get-go. After a month or two, the degradation starts affecting the fuel and vehicle.
Much of this confusion relates to E10 petrol.
E10 is the ‘new’ standard grade in the UK starting September 2021. It is priced cheaper than its predecessor – E5 petrol. Before we discuss the characteristics of bioethanol blends, let’s talk about petrol in general.
Petrol has a six-month shelf life if stored in the right conditions.
The right conditions include storing it in a tightly sealed container at 20 degrees. The rate at which petrol degrades is directly proportional to the temperature it is exposed to.
For instance, if petrol lasts for six months at 20 degrees, it lasts half of that at 30 degrees. So, there is an exponential drop in the shelf life.
Does E10 petrol have a shelf life
E10 petrol has a shelf life of up to 3 months when stored in a tightly sealed container, after which you may find it turning green. The same applies if you store E10 in the fuel system or gas tank of an unused vehicle.
Unused implies that there is no circulation of the fuel for a prolonged period. Or, in other words, a vehicle that is not used for weeks as it lies parked away in a garage.
Petrol, every grade of it, is considered fresh for up to 60 to 90 days. After six months to a year, the petrol is out of date.
‘Old gas’ in a car can lead to clogged injectors, engine knocking, and other potentially damaging issues. But things are a little different with E10.
- E10 petrol is an ethanol-blended fuel, made of 90% petroleum and 10% bioethanol. Ethanol oxidizes at a rapid rate, which is why the American Energy Information Administration states that E10 petrol has a shelf life of three months.
Does 91 Petrol last longer than E10
91 petrol or standard unleaded petrol has a shelf life of 6 to 8 months when stored at the right temperature (20 degrees) in a sealed container. It is considered fresh for 2 to 3 months in the fuel tank, after which it begins to degrade. This is significantly higher than the shelf life of E10 fuel, which is around the 3-month mark.
91 is the Research Octane Number (RON) that indicates the octane rating of standard unleaded petrol. The octane ratings for different grades of petrol are as follows:
- E5 Super Unleaded: 98 octane
- Premium Unleaded: 95 octane
- E10: 94 octane
- Standard unleaded: 91 octane
The stats for fuel economy tow the same line.
Price-wise, E10 is cheaper than 91 petrol.
91 Petrol or standard unleaded petrol has a 91 octane rating. E10 ranks higher with 94 octanes. In theory, your engine should perform better on E10. But ethanol in the blend lowers the energy levels by 30%, which results in slightly less fuel economy.
Does E10 damage your engine
E10 is safe to use for most cars made after 2010, which qualify as E10 compatible vehicles.
All vehicles sold in the European Union need to be E10 compatible as per 2010 EU regulations. E10 can damage the engine of incompatible cars, potentially older and classic cars.
- Ethanol can cause significant damage to the plastic, rubber, and metal components.
According to UK’s Department for Transport, the tests conducted on E10 indicate that it causes degradation of fuel pipes, seals, and rubber components. The official documents also acknowledge injector and fuel filter blockages, damaged fuel pumps, and fuel tank corrosion.
As we discussed earlier, E10 has a relatively higher percentage of ethanol.
Bioethanol is known to corrode gaskets, rubber components, metals, and plastics. Besides engine damage, it may also lead to blockages in older engines.
Firstly, ethanol can degrade plastic and rubber components as it is a solvent. This includes filters, rubber seals, fuel lines, among other things.
Secondly, ethanol is hygroscopic – it absorbs water from the atmosphere. This leads to condensation and subsequent corrosion in metal components.
It’s not doom and gloom because car manufacturers have accounted for these changes.
E10 is new to the UK but has been used in America, Australia, and Europe for quite a while now. The first thing you should do is check online if your vehicle can safely use E10 petrol.
How to check if your car is E10 compatible
All drivers should refer to the owner’s manual (V5C log book) to check if your car is cleared for E10 use.
You need to know the vehicle manufacturer, engine size, model, and year of manufacture to use the UK government’s online service.
France, Germany, and other EU nations have been using E10 petrol since 2016.
A few exceptions exist, which include models by Audi, Mercedes, Volkswagen, and others. As for the UK, some estimates suggest there are between 600,000 to a million cars (actively used) that are not E10 compatible.
E10 has more ethanol than E5, the standard petrol in the UK until September 2021. The different compositions can pose a significant risk to incompatible cars. With a few odd exceptions, most cars made in 2011 or after should be compatible with E10.
Is E10 safe for Cars older than 2002?
No, the UK Government and car manufacturers advise against using E10 petrol to fuel a non-compatible vehicle.
It may cause mechanical damage and corrosion. Even if your car was made after 2002, it is worth double-checking to ensure there won’t be issues with your specific engine.
Older or ‘classic’ car owners should take a few extra measures. For instance, they can continue to use 91 petrol or add lead replacement additives or ethanol stabilizers to E10 fuel to prevent corrosion.
What to do if you accidentally use E10 petrol in an incompatible car
Misfuelling a non-compatible car with E10 once is not a cause for panic.
It may cause temporary problems such as rough running and cold starting. You can proceed to use the correct petrol grade the next time you tank up.
Some car insurance brands warn that E10 petrol may lead to substantial damage to the engines of old and/or incompatible cars.
People should not worry about immediate damage to after an instance or two.
The problem only applies to continuous, long-term misfuelling. If you own a classic car, things may be a little more complicated. You don’t want E10 petrol sitting in your tank as it can damage components, which can be expensive to replace in a classic car.
As per the European Automobile Manufacturer’s Association, contact the manufacturer or roadside assistance to drain the fuel tank if you accidentally fill up classic cars with E10 petrol.
Does E10 petrol make your car slower?
E10 is praised heavily by environmental groups, but not for its efficiency. They focus on the CO2 emission targets and the carbon-offsetting properties of ethanol. Objectively speaking, E5 is more efficient than the E10 blend of fuel.
Repeated use of E10 in an incompatible car will damage and corrode engine parts. This, of course, will result in a loss of performance. Even if your car is E10 compatible, you should expect fewer miles to the gallon. Pure unleaded petrol has 33% more energy content than E10.
The exact number varies based on the denaturant added to ethanol, but either way, it will negatively impact the fuel economy.
According to a UK government estimate, there will be a 1% decrease in MPG (miles per gallon) for cars that shift from E5 to E10. The Energy Information Administration (USA) estimates that fuel economy may fall by 3% with E10 usage.
Non-compatible cars need to use super unleaded E5 petrol that is still available at filling stations across the UK. It comes with an uptick in costs. The costs can mount up if you travel far to get to work each day. This is one of the challenges of reducing emissions.
Does E10 Petrol Work in Petrol Lawnmowers?
I have written a separate article that covers everything you need to know regarding E10 and garden equipment. You can read it here.
Petrol has been around for a while, but things have significantly changed in the past decade. Hopefully, this article sheds light on the impact these changes will have on your car and pocket. I’ll leave you with a quick recap of the main points covered in this article –
- E10 Petrol has a shelf life of 3 months if stored in a tightly sealed container at 20 degrees.
- 91 Petrol has a shelf life of 6 months if stored properly.
- E10 is safe for E10 compatible cars, those manufactured after 2011.
- E10 petrol should not be used for cars made before 2002.
- Ethanol in E10 can cause damage or corrosion in engine parts.
- People should check if the car can run on E10 petrol before using it.
- E10 petrol gives fewer miles to the gallon compared to E5 petrol.