Top Petrol Choices for Classic Cars in the UK: Best Fuels for Performance and Preservation

For classic car owners, selecting the right petrol isn't merely a matter of what's available at the local forecourt - it's a crucial decision that directly impacts engine performance, longevity and preservation of these cherished vehicles. With the UK's evolving fuel landscape and increasing ethanol content in standard fuels, understanding the optimal choices has never been more critical.

The Ethanol Challenge

Modern unleaded petrol in the UK now commonly contains up to 10% ethanol (E10), which presents several challenges for classic vehicles:

Ethanol is hygroscopic, meaning it absorbs moisture from the atmosphere
It can deteriorate rubber components, seals and gaskets in fuel systems not designed for ethanol
It has a shorter shelf life than traditional fuels
It can lead to corrosion in fuel tanks, carburettors and fuel lines
It potentially offers lower energy content, resulting in reduced power and fuel economy

Classic cars manufactured before the 2000s typically weren't designed with ethanol-blended fuels in mind. Introducing E10 as the standard unleaded grade for these vehicles has created genuine concerns among enthusiasts and collectors.

Premium Fuel Options for Classic Cars

Super Unleaded (E5)

Many UK filling stations continue to offer super unleaded (97+ RON) with lower ethanol content, typically at E5 (5% ethanol). While more expensive than standard unleaded, this fuel provides:

A higher octane rating, which is beneficial for higher-compression engines
Lower ethanol content, reducing the potential for material degradation
Better storage stability
Improved performance characteristics

Major brands such as Shell V-Power, BP Ultimate, Esso Supreme and Texaco Supreme offer 97-99 RON super unleaded options with reduced ethanol content compared to standard grades.

Ethanol-Free Specialist Fuels

For particularly valuable or sensitive classics, specialised ethanol-free fuels represent the gold standard:

Esso Synergy Supreme+ Unleaded 97: While not entirely ethanol-free, this premium fuel contains significantly lower ethanol levels than standard fuels and includes additives that help protect against corrosion and deposit build-up.

Anglo American Oil Company's Sunoco Optima 98: A high-quality, ethanol-free fuel specifically formulated for classic cars. Its 98 RON octane rating is suitable for high-compression engines and contains additives to protect fuel systems.

Carless Hiperflo 300: A specialist racing fuel that's ethanol-free with a high 102 RON octane rating, making it excellent for high-performance classic engines, though at a premium price point.

Classic Fuel Solutions' Ethanol-Free Unleaded: Available in 5-litre and 25-litre containers, this specially formulated fuel is completely ethanol-free and designed explicitly for classic vehicle preservation.

Managing Ethanol Content with Additives

When specialist fuels aren't practical or available, fuel additives provide a valuable alternative.

Castrol Classic Valvemaster Plus: Particularly valuable for classics running on unleaded fuel that were initially designed for leaded petrol, this additive:

Protects valve seats
Helps neutralise ethanol's corrosive effects
Improves fuel stability during storage

We also offer a Dynolite alternative - GGL872102.

Ethanol Fuel System Treatment: Formulated specifically to address ethanol-related issues, this treatment

Removes water from the fuel system
Prevents corrosion
Cleans fuel injectors and carburettors

Consider the following products:

Seasonal Considerations and Storage

Classic cars in the UK often see limited use during winter months, making fuel storage characteristics particularly important:

For vehicles used year-round, maintain a topped-up tank using super unleaded where possible
For vehicles stored over winter, either fill the tank completely with high-quality, low-ethanol fuel and add a stabiliser or drain the system entirely if storage will exceed six months

Consider the following products:

When recommissioning after storage, replacing old fuel if it's been in the tank for more than 3-4 months is advisable.

Practical Recommendations

Based on current UK availability and classic car requirements:

Daily or regular use: Super unleaded (E5) from major brands offers the best compromise between availability and suitability
Show cars and occasional use: Consider specialist ethanol-free fuels, particularly if the vehicle has original rubber components or is especially valuable
All classic vehicles: Use appropriate fuel system additives regardless of fuel type to provide additional protection
Winter storage: Implement proper fuel management strategies to prevent degradation during storage periods

The correct fuel choice depends on the vehicle's age, condition and usage pattern. Owners of particularly rare or valuable classics should consult with marque specialists regarding the optimal fuel strategy for their specific vehicle.

Making the Right Choice for Your Classic

Ultimately, the decision comes down to balancing authenticity, performance, practicality and preservation. While specialist fuels represent the ideal solution, particularly for pre-1980s vehicles, the conscientious use of super unleaded with appropriate additives represents a practical approach for most classic car enthusiasts.

Clearly, standard E10 petrol should be avoided where possible in vehicles not certified as compatible. Marginal cost savings rarely justify the potential long-term impacts on engine components and performance.

Looking to protect your classic from the challenges of modern fuels? Rimmer Bros offers a comprehensive range of fuel additives, treatments and specialist products designed specifically for classic vehicles. Browse our fuel management range to find the perfect solution for your cherished classic.