Petrol 95 vs 98: Is the Price Difference Worth It?

The octane rating, which we see marked on fuel pump nozzles as 95 or 98, represents the fuel's resistance to self-ignition under pressure. In short, a higher number indicates greater resistance of the gasoline to igniting spontaneously, before the spark plug fires. This phenomenon, called detonation or "knocking," can be extremely damaging to the engine, causing premature wear and reducing efficiency.

Modern engines are designed with specific compression ratios that dictate the type of gasoline required. Gasoline with an octane rating too low for a given engine will cause knocking, while one with a higher octane rating than necessary will not provide any additional benefits for most cars. It is, therefore, a vital technical characteristic, not merely a simple classification.

The fundamental difference between 95 and 98 octane petrol is, as explained, knock resistance. 98 octane petrol is formulated to withstand higher pressures and temperatures in the engine cylinder before igniting, making it ideal for engines with a high compression ratio or those fitted with turbochargers, where cylinder pressure is much greater.

For an engine designed to run on 95 octane petrol, using 98 octane will generally bring no noticeable benefit in terms of power or fuel consumption. The car's electronic systems, through knock sensors, will adjust the ignition timing anyway to prevent knocking, regardless of the fuel used, but they cannot "create" extra power from nothing. Furthermore, the average price of 95 octane petrol today is 8.66 lei/L — even a difference of a few bani per litre compared to premium fuel prices will be felt over a full tank.

The use of 98 petrol is absolutely necessary in two main situations: first, when the car manufacturer specifies this in the technical manual. High-performance, sports, or engines with advanced technologies (such as direct injection combined with turbocharging at high pressures) are often designed to operate optimally only with high-octane petrol. Failure to follow this recommendation can lead to frequent knocking, engine damage, and loss of warranty.

Second, 98 petrol is recommended for modified cars ("tuned") or those used in extreme conditions, such as racing. In these scenarios, the engine is subjected to much greater stress than in normal traffic. For standard cars that do not fall into these categories, a 50 L fill-up with 95 petrol, at an average cost of 433 lei, is the correct and economical solution.

For a standard engine that the manufacturer designed to run on 95 octane petrol, using 98 octane brings no significant benefit. It is a widespread myth that a higher octane rating automatically means more power or lower consumption, but the technical reality is different. The car's electronic system, through the engine control unit (ECU), is calibrated to optimise combustion for 95 octane petrol. The knock sensors will detect any tendency toward pre-ignition and will adjust the ignition timing, but they cannot fully exploit the potential of a higher-octane fuel if the engine was not designed for it.

In practice, you will pay more for a premium fuel without obtaining any noticeable improvement in performance or a reduction in consumption. Given that the average price of 95 octane petrol is 8.66 lei/L, any additional price premium for 98 represents an unjustified expense for most drivers. Instead, focus on finding stations with better prices for 95 octane petrol; the maximum price difference between stations can reach 0.83 lei/L, and that is what truly matters for your wallet.

Although we do not explicitly track the average price for 98 octane petrol separately, our experience on the fuel market — where we monitor prices across 1390 stations nationwide — shows that 98 octane or higher petrol always commands a higher price than the standard 95. This difference varies from one retailer to another and from one station to another, but it typically amounts to a few tens of bani per litre.

Even an apparently small difference — say, 0.50 lei/L — adds up quickly. For a full tank of 50 litres, that means 25 lei extra. Compared with the average price of 95 octane petrol at 8.66 lei/L, or even with the 0.83 lei/L spread we can find between stations selling the same type of 95 octane petrol, any additional cost for 98 should be assessed in the real context of your vehicle's needs.

Some drivers choose to pay more for 98 petrol even when their car's engine doesn't require it, often due to a combination of factors: marketing, the perception that "more expensive means better," or simply out of habit. Oil companies invest in promoting premium fuels, highlighting special additives that promise engine cleaning or a longer lifespan. Although these additives may bring marginal benefits, they are rarely decisive if the car is properly maintained.

However, the most important aspect is the technical one. If your engine is calibrated for 95 petrol — meaning it has a lower compression ratio — it simply will not be able to take advantage of the additional knock resistance offered by 98 petrol. You are paying for a feature that the engine does not use, similar to buying Formula 1 tyres for a trip to the supermarket. With an average price of 95 petrol at 8.66 lei/L and a 50 L fill-up at 433 lei, every extra leu should have a solid justification.

Using gasoline with an octane number that is too low for your engine's specifications poses serious risks. The most common and dangerous is the phenomenon of detonation or "knocking", where the air-fuel mixture ignites spontaneously due to high pressure and temperature, before the spark plug fires. This uncontrolled combustion creates shock waves that strike the engine's internal components, such as pistons and connecting rods, which can lead to major and costly damage in the long run.

Even though modern engines are equipped with knock sensors that automatically adjust ignition timing to minimise the effects, this comes at a cost. The adjustments lead to a reduction in performance and an increase in fuel consumption, because the engine is no longer operating at optimal parameters. So, instead of saving money, you risk spending more on repairs and having a below-standard driving experience. It is therefore essential to follow the manufacturer's specifications for the type of fuel.

In general, if your car's engine is designed for 95 petrol, you can occasionally alternate with 98 petrol without encountering major problems. The engine management system (ECU) is smart enough to adapt to minor differences in octane rating. However, it is important to understand that you will not obtain any real benefit from using 98 petrol, as previously mentioned, and your wallet will feel the price difference.

On the other hand, if your car strictly requires 98 petrol, frequent alternation with 95 can be harmful in the long run, causing knocking and wear. Our recommendation is to always consult your car's manual and respect the fuel type specified by the manufacturer. With a price difference of 0.83 lei/L between stations selling the same 95 petrol, finding the best deal for the correct fuel type is far more efficient.

Finding the best prices for 95 petrol is a priority for most drivers, especially when the average price is 8.66 lei/L and a 50 L fill-up comes to 433 lei. On PretCarburant.ro, we constantly monitor prices across 1390 stations nationwide, giving you a clear and up-to-date picture of the market. It is remarkable that there is a difference of up to 0.83 lei/L between the cheapest and most expensive 95 petrol, even in relatively nearby cities.

Using the interactive map or our minimum prices list, you can quickly locate the stations offering the most advantageous rates in your area. This tool allows you to save significantly on every fill-up, without compromising fuel quality. A simple check before heading out can save you considerable sums over the course of a year.