A seasoned mechanic has issued a stark warning to UK motorists, urging them to avoid a common refuelling mistake that can have devastating and expensive consequences for their vehicles.
Marcus Martin, an experienced mechanic and social media influencer known as @the_vehicle_doctor, has highlighted a critical error many drivers make at the pump. His warning comes as more drivers than ever are filling up with the newer, greener E10 petrol without fully understanding its potential risks.
The Hidden Danger in Your Fuel Tank
The core of the issue lies with the ethanol content in modern petrol. Since its introduction in 2021, E10 has become the standard grade at forecourts across Britain. While it's a more environmentally friendly option, its higher ethanol blend (10% compared to E5's 5%) can be a silent killer for engines, particularly in older models.
'I've seen it time and time again,' Marcus explains. 'A car comes in with a rough idle, loss of power, or it simply won't start. The culprit is often water contamination in the fuel system, and the ethanol in E10 petrol accelerates this problem dramatically.'
Why You Should Never Run Your Tank to Empty
The mechanic's primary advice is simple: never let your fuel level drop into the red or onto the reserve light. Here’s why:
- Condensation Build-Up: A near-empty tank has more air space. This air contains moisture, which condenses on the cool walls of the tank, especially during the UK's fluctuating weather. This water then mixes with the ethanol in the fuel.
- Ethanol is Hygroscopic: This means it actively attracts and absorbs water from the atmosphere. Low fuel levels give it more opportunity to do so.
- Phase Separation: When too much water is absorbed, the ethanol and water mixture can separate from the petrol, sinking to the bottom of the tank. This watery ethanol mix is what your fuel pump will draw into the engine.
The Catastrophic Consequences for Your Engine
Pumping this corrosive cocktail through your fuel system can lead to a cascade of failures:
- It can clog fuel filters and injectors with a sticky, gel-like substance.
- It causes rapid corrosion of vital metal and plastic components within the fuel pump and system.
- This contaminated fuel burns poorly, leading to misfires, a rough running engine, and a significant loss of power.
- In severe cases, it can cause complete engine failure, requiring a full fuel system flush or replacement.
'The repair bills can easily run into the thousands,' Marcus warns. 'A new fuel pump alone can be hundreds of pounds, before you even factor in labour, new filters, and injector cleaning. It's a financial nightmare that is easily avoidable.'
How to Protect Your Car and Your Wallet
Marcus advises drivers to adopt a few simple habits to prevent this expensive damage:
- Keep Your Tank Topped Up: Make it a habit to refuel once your gauge hits the quarter-tank mark, especially during humid or cold weather.
- Consider E5 Premium Fuel: For older cars, classic cars, or those that are rarely used, opting for the super-unleaded E5 petrol (which has half the ethanol) is a much safer bet, despite the higher cost per litre.
- Use a Fuel Additive: For peace of mind, consider using a fuel stabiliser or ethanol treatment, particularly if the car will be left unused for extended periods.
This expert advice serves as a crucial reminder that a small change in driving habit can save British motorists from unforeseen and massive repair costs, keeping their vehicles running smoothly for longer.
