What’s the Difference Between 93 and 95 Unleaded Petrol?

·       93 and 95 refer to the octane rating of petrol.

·       Octane rating measures resistance to engine knock — not fuel strength.

·       Most standard vehicles inland can safely use 93.

·       High-compression or turbocharged engines usually require 95.

·       Always follow your vehicle manufacturer’s recommendation.

Now let’s unpack that properly.

Octane rating measures a fuel’s ability to resist engine knock — also called pre-ignition or detonation. Knock occurs when fuel ignites too early inside the engine cylinder, creating pressure spikes that can damage components over time.

Higher octane fuel doesn’t contain more energy. It simply burns in a more controlled way under higher compression.

Engines that typically require 95 octane include:

·       Turbocharged petrol engines

·       Performance vehicles

·       High compression ratio engines

·       Some newer European imports

If your vehicle is designed for 93, using 95 won’t usually give noticeable benefits. But if your vehicle requires 95 and you consistently use 93, long-term engine stress may occur.

South Africa’s geography plays an important role in fuel availability.

Fuel standards and grades are regulated by the Department of Mineral Resources and Energy, which oversees petrol classifications and national fuel policy.

At higher altitudes — like Gauteng and much of the Highveld — air pressure is lower. Lower air pressure reduces engine compression naturally, which decreases the likelihood of knocking. Because of this, 93 octane is widely available inland.

At sea level — such as KwaZulu-Natal and Western Cape coastal areas — air pressure is higher. Engines operate under greater compression, increasing the need for higher knock resistance. That’s why 95 octane is more common at the coast.

If you travel between inland and coastal provinces, modern engine management systems typically adjust automatically. However, your safest option remains following your manufacturer’s specified minimum octane.

This is one of the biggest fuel myths.

Higher octane does not mean:

·       More power

·       More speed

·       Better fuel quality

·       Cleaner combustion

It simply means better resistance to premature ignition.

If your engine is tuned for 95, then yes — it may perform optimally on 95. But if it’s designed for 93, switching to 95 won’t unlock hidden performance.

In short: suitability matters more than superiority.

Not automatically.

Fuel consumption depends on:

·       Driving style

·       Vehicle weight

·       Traffic conditions

·       Engine design

·       Tyre pressure

If your vehicle requires 95, using the correct octane allows it to operate efficiently. But using 95 in a vehicle designed for 93 won’t suddenly improve mileage.

Fuel prices fluctuate monthly, and inland and coastal pricing can differ. The Automobile Association (AA) fuel price updates provide regular commentary on national fuel price adjustments and regional differences.

Because 95 is often slightly more expensive, using it unnecessarily may increase your monthly fuel costs without providing benefits.

Let’s separate the two situations.

Using 93 in a 95-Required Engine

If it happens once:

·       Your vehicle may adjust ignition timing automatically.

·       You may notice reduced performance.

·       Occasional use is unlikely to cause immediate damage.

Repeated use, however, could increase wear over time — especially in turbocharged engines.

Using 95 in a 93-Recommended Engine

This is generally safe.
You’re unlikely to see measurable benefits, but you won’t damage your vehicle.

The real concern is not octane differences — it’s using the wrong fuel type entirely (for example, petrol in a diesel engine). That can cause serious mechanical damage. If that ever happens, you can read our guide on what happens if you fill your car with the wrong fuel.

Yes.

Mixing 93 and 95 petrol in your tank does not cause harm. The result will simply be an averaged octane rating.

For example:

·       Half tank of 93

·       Half tank of 95

·       Results in approximately 94 octane

Modern engines are designed to handle small variations without issue.

The safest way to determine the correct fuel is to check your owner’s manual and follow your vehicle manufacturer’s recommendation.

You can also:

·       Check inside the fuel cap

·       Contact your dealership

·       Look up manufacturer specifications online

If your car specifically states “Minimum 95 RON,” then you should use 95 consistently.

If it states “93 or higher,” then 93 inland is typically suitable.

When in doubt, follow the manufacturer — not hearsay at the pump.

Myth: 95 is better for all cars.
Truth: Only engines designed for 95 benefit from it.

Myth: 95 gives more power in any vehicle.
Truth: Only high-compression engines may see performance optimisation.

Myth: Using 93 at the coast will destroy your engine.
Truth: It depends on your manufacturer’s minimum requirement.

Myth: Higher octane cleans your engine.
Truth: Cleaning additives depend on brand formulation, not octane number.

Using the correct octane:

·       Supports engine longevity

·       Preserves performance

·       Maintains resale value

·       Reduces risk of knock-related wear

Small, consistent decisions — like using the correct fuel — contribute to lower long-term vehicle costs.

Understanding how your engine works helps you make smarter choices at the pump.

The difference between 93 and 95 unleaded petrol isn’t about which fuel is superior — it’s about compatibility.

·       Octane rating measures knock resistance.

·       Inland and coastal differences relate to altitude.

·       Higher octane doesn’t mean more power.

·       Manufacturer guidance should always be your primary reference.

Choosing the correct fuel is a simple step that supports long-term vehicle health and predictable running costs.

Looking after your vehicle goes beyond what you put in the tank. From accidental damage to unexpected breakdowns, having the right protection in place gives you confidence on every journey.

Get a tailored car insurance quote in minutes or request a call back from a MiWay consultant today — because protecting your car should be just as straightforward as filling up.