Why 95 petrol is better for your car – even at R30 per litre

Petrol 95, or 95-octane unleaded, benefits different vehicles in various ways, though not always in the ways motorists think, often making it the better choice, even at R30 per litre.

Despite the myth that unleaded fuel’s octane rating affects how much energy or “power” is packed into the fuel, it simply represents how stably the fuel burns before spontaneous, uncontrolled combustion occurs.

This benefit is enhanced at sea level, where atmospheric air is dense and oxygen-rich, and 95-octane petrol can help prevent engine knock.

When drawn into the engine’s cylinders, this denser charge creates higher effective combustion pressures, preventing premature ignition under these conditions, which is why coastal forecourts exclusively sell petrol 95.

Car manufacturers also recommend motorists refuel turbocharged and high-compression cars with 95-octane unleaded petrol, even downsized commuter cars with 1.0l to 1.5l turbocharged petrol engines.

That is because modern Engine Control Units (ECUs) continuously monitor for knock using acoustic sensors.

On 95 octane, the ECU can advance ignition timing to its maximum factory calibration, delivering the full advertised torque and horsepower.

If a car’s manufacturer specifies a minimum of 95 and you fill up with 93 inland, the ECU detects micro-knocks and automatically delays the ignition timing to protect the engine.

While this prevents catastrophic damage, it reduces thermal efficiency and forces the engine to burn more fuel to maintain speed, so using 95 prevents this timing penalty, preserving optimal fuel consumption.

Sustained detonation under heavy load, such as towing a trailer, climbing mountain passes, or aggressive acceleration, generates violent shockwaves.

Over time, this causes cracked piston rings, pitted valves, and damaged spark plugs. Using 95 provides the thermal stability needed to prevent long-term mechanical wear.

As a result, using the right octane petrol also protects engine components long-term and maintains a vehicle’s resale value.

93-octane will work fine for some

According to Elri Volsteedt, Sasol’s Head of Customer Technical Services, South African motorists are under growing pressure to manage everyday travel expenses without compromising vehicle performance.

“For vehicles that can perform with 93‑octane unleaded petrol, choosing 93 instead of 95‑octane can deliver meaningful savings over time, while meeting manufacturer performance requirements,” she said.

While recent media coverage suggests that 93-octane unleaded petrol may be disappearing from the market, Volsteedt assured that it will continue to be produced locally.

Sasol produces 93-octane locally through an integrated fuels value chain, supporting reliable availability at service stations to meet ongoing demand.

Volsteedt explained that for vehicles designed to operate on 93-octane unleaded petrol, the fuel is functionally equivalent to 95-octane unleaded in terms of quality and engine protection.

“Detailed analysis by Sasol, drawing on vehicle population data, manufacturer owner’s manuals and fuel‑filler specifications, indicates that a significant proportion of petrol vehicles operating inland are compatible with 93,” she said.

“This includes most Japanese brands, many European vehicles configured for inland conditions, a large share of Korean models specifying a minimum of 91 octane, and a growing number of Chinese brands typically requiring 92 octane.”

It is also important to realise that the compatibility she speaks of is not limited to older vehicles in South Africa.

That is because many modern engines, including turbocharged models where the manufacturer specifies 91-octane minimum, are designed to operate safely and reliably on 93-octane under local inland conditions.

Volsteedt explained that the same applies to a significant portion of the petrol minibus taxi fleet operating on South Africa’s roads.

“The price difference between 93 and 95 is regulated and adjusted over time in line with international benchmarks,” she added.

“This differential has at times reached 46 cents per litre, reinforcing the long‑term value proposition of 93-octane unleaded petrol for suitable vehicles.”