The speedy transition can cause problems for the engine, one of which is sluggish performance, engine damage and even difficult to start-up. Likewise, frequently changing fuel brands. Each manufacturer has a different configuration, therefore this type of differences can shock the engine and cause a serious problem.
Mixing the grades to get 91 or so shouldn't hurt, but it probably isn't saving you much money. Using anything higher than your manual recommends probably won't help your car's performance – but using lower might save you a few bucks, Leroux says. If you notice knocking, you should switch back.
It is okay to mix fuels (except for diesel) in your car as long as the octane rating is not less than the recommended fuel you should use. For example, if you have a car that takes 91, then mixing with 95 is fine, but not the other way round. A car that takes 95, can only mix with fuels that are higher like 98.
Can you mix regular unleaded and premium unleaded? Yes, certainly. If your tank is not empty, you can safely mix premium unleaded and unleaded petrol. Mixing the two will average out the octane rating, so it won't lead to any damage but it will decrease the full potential of the premium unleaded fuel.
Mixing the 95 and 98 octane fuels will not cause any problems.
For example, putting regular unleaded 91 RON in a car designed for the higher-octane 95 RON or 98 RON could result in knocking in the engine. You may hear unusual sounds or experience a less smooth drive, and in the long run it could diminish fuel economy.
Using 98 might give 3 per cent reduction over 95, again assuming the computer adjusts the engine parameters. But fueling an engine with 95 or 98 won't necessarily open the door to earth shattering performance or extreme levels of fuel economy if the engine is not specifically designed to run on it.
Basically, it is still fine changing to another fuel if just for one time filling only during an empty tank situation. The reason is, all types of fuel have the same constituent elements on the hydrocarbon chain, so it is relatively safe if 1-2 types of fuel mixed in one tank.
CAN I MIX E10 AND REGULAR UNLEADED? Not like diesel and petrol, you can refuel with E10, regular or premium unleaded without any damage to the fuel system or engine.
If your vehicle is compatible with E10 petrol, there's no reason you can't mix the 2 grades of petrol (E5 97+ and E10 95+).
If 91 is used in cars requiring higher octane fuel, you run the risk of pre-igniting or "knocking". This occurs when the petrol combusts early and pushes down against a piston while it is still moving upwards during the compression stroke.
No problem with putting 95 or even 98 in a car designed for 91 – except generally you will be wasting money. Higher octane fuels don't contain more energy. Octane rating is basically resistance to burning under pressure, allowing higher compression ratios to be used (cylinder pressures, actually).
Engine Protection
98 petrol, which is more stable and resistant to 'knocking', is a better choice when it comes to engine protection. 95 petrol works as well, but if your engine is powerful, it will use higher pressures that 95 petrol may not be able to withstand.
The general rule of thumb is: the difference in fuel efficiency is about 1% per octane rating – 91 and 95 unleaded fuels, for example, have roughly a 4% difference. If there is a lesser price difference between the two, then its highly likely that its worth switching.
Depending on the car you own, fuelling up with 98 octane can result in increased performance that will see you produce a little extra power when compared to lower octane petrol. But if you're driving something older that hasn't been tuned to run on high-octane, you'll likely see no tangible benefit.
Do I get the same fuel economy out of E10 as regular unleaded petrol? At the pump, E10 is generally the cheapest petrol per litre. Because the energy provided by the ethanol is less than the energy provided by pure petroleum, E10 has around 3% less energy than the equivalent amount of RON 91 petrol.
The octane rating of fuel is a reference to its resistance to premature detonation or knocking. The higher the rating, the less likely it is to combust under pressure, and thus the more suitable it is for high-compression and turbocharged engines.
Short answer. If your car needs only the lower octane gasoline, then you can use that OR ANY HIGHER OCTANE gasoline/petrol. Your engine won't know the difference between the required octane rating, or anything higher than that.
Yes, drivers can mix the two types of fuel. The combined gas types will result in an octane level somewhere in the middle — something the vehicle “will survive,” according to The Drive.
Can you mix unleaded and superunleaded? Yes. All current cars are designed to run on standard 95 octane unleaded (even high-performance cars) but will run equally well – if not better – on the higher octane superunleaded, which has an octane rating of 97 or above.
bp Ultimate Unleaded is our most advanced performance petrol with a minimum octane number of 98 and an innovative formulation that cleans away the harmful dirt in your engine and helps stop it coming back.
Can I mix E10 and regular unleaded? Not like diesel and petrol, you can refuel with E10, regular or premium unleaded without any damage to the fuel system or engine.
In summary, the fuel efficiency of the 95-Octane vs the 98-Octane are rather comparable. The 98-Octane fuel is generally more efficient, allows for greater engine protection and reduces the environmental impact only if the engine of rented cars are equipped to handle the higher quality fuel.
What's the difference between 91 and 95 octane fuel? Put simply, the only difference between these two fuels is their Research Octane Number, with the higher-octane 95 unleaded designed to be more fuel efficient and lead to a smoother engine operation.