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 can't hurt your engine if you use a higher octane fuel. So, for example, if you use 95 or 98 in an engine designed for 91, that's OK. However, it's not acceptable to put in a lower octane fuel than the minimum recommended by the manufacturer. Using 91 in an engine designed for 95 or 98 is potentially destructive.
If you're driving a car that takes 91 unleaded and you fill up with a premium 95 or 98 fuel, don't panic as this won't lead to any engine damage. You may just not a difference a little less cash in your wallet.
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.
Yes, you can mix both regular and premium petrol. Since both the fuels are unleaded, it will not cause any harm to your car's engine.
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.
Different octane fuels can mix together OK so won't do any harm. If the vehicle is designed to run on 91, you're usually best to stick to that as there's generally no benefit in running a more expensive, higher octane fuel.
If you usually fill your tank up with 87-octane gasoline and you accidentally put in a higher octane blend (say, 91, 92, or 93), don't worry. You're actually filling your car or truck with a different blend of gas, which means it will burn differently in your engine.
By mixing higher with lower RON octane, the sulphur and all the additive substances of the higher octane fuel will be lost in the mix. This can lead to severe problems in the engine, as the RON decreases, engine performance is diminishing. To maintain the same performance the engine will need more fuel.
The difference between each fuel type is their 'octane rating', or the numbers that identify them, such as 91, 95 or 98. The octane rating is an index of a fuel's heat resistance, which means the fuel's ability to resist premature burning, which can cause your engine to 'knock'.
According to NRMA motoring expert Jack Haley, on average 95 RON can give around 4 per cent lower fuel consumption than 91, assuming the engine computer adjusts to take advantage of the octane difference. Using 98 might give 3 per cent reduction over 95, again assuming the computer adjusts the engine parameters.
Mixing E10 and E5 petrol
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+).
Many cars will print an advisory label on the inside of the fuel filler cap that notes the minimum fuel quality required by the engine, and while it's not recommended to go lower, is there any risk to going higher? Bottom line, no. There is no risk when putting higher-octane fuel in your petrol car.
The higher octane gives premium gas greater resistance to early fuel ignition, which can result in potential damage, sometimes accompanied by audible engine knocking or pinging.
Otherwise known as Ultra-Premium by some brands, 98 is the highest-octane fuel currently available in Australia. Unleaded 98 provides higher engine power and overall performance in comparison to 91 and 95. It is also responsible for less pollution, according to providers.
Mixing the 95 and 98 octane fuels will not cause any problems.
Raising the octane rating (also known as the anti-knock index) doesn't change the energy content of a gallon of gasoline. A higher octane rating indicates greater resistance to knock, the early combustion of the fuel-air mixture that causes cylinder pressure to spike.
Using a lower octane fuel for a premium-required vehicle may sometimes lead to internal damage. In some cases, you may notice rattling noises, decreased fuel economy, and reduced efficiency and performance from your engine. If you accidentally put in a lower octane fuel in your tank, it doesn't hurt to use it up.
Engine computers can usually adjust their timing to account for the increased octane levels, so if you put premium gas in a regular car, you probably won't notice anything. However, some engines are not designed to burn higher-octane fuel, and you may see a reduction in performance and fuel economy.
Brannon noted that most cars are equipped with sensors that can help certain vehicles run on lower-octane gas even if they're built for premium gas, but switching gas can still cause damage. "It's really not a good idea," he said. "The engine may not be able to adjust (to regular gas)."
The car will run on regular fuel in a pinch, but you shouldn't make a habit of it. The fuel's lower octane can result in elevated exhaust-gas temperatures and possible knocking, both of which can adversely affect the engine's health in the long run.
A higher-octane rating means the fuel is better balanced and stabilized against spontaneous combustion, which can cause engine knocking and damage to your vehicle.
Yes, they will mix just fine. The question is why would you mix them? If the car is designed to use 91, you won't harm it by mixing in some higher octane fuel, but you'll get no benefit at all.
If, for example, your car says 'premium 95', then it is not recommended to use unleaded 91, as doing so can cause engine knocking and potentially engine failure.
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.