Premium fuel

[Austin plays]

Premium fuel and yes, premium fuel. Does it actually make a regular car run any better or is it just for performance engines? Please reply only if you personally have tested! Thnx

 

[TheCracker]

Engines with a high compression ratio often require premium (high octane) fuel. High compression engines are not necessarily 'performance' engines.

My previous car required high octane fuel but i could run it on regular. The car recognises the lower octane fuel and adjusts the ignition to suit it. You can feel a slight reduction in performance though and it felt much happier on premium.

 

[Austin plays]

So was the difference more like power or just how smooth it felt? And have you check it on any suzuki car, specifically, suzuki V6 escudo pikes? This car's look is just crazy! Do you even know that suzuki is not only a car brand, it's also on the list of S-starting Japanese names.

 

[TheCracker]

So was the difference more like power or just how smooth it felt?

Both really, but unless you are contantly thrashing the engine you feel it more as a slight hesitation in the delivery of power at different throttle imputs. It just doesn't feel quite 'right'.

Think of it as your car is at 100% when using premium. On regular it's not quite the same. I don't know by what percentage it actually makes a difference, or whether its the same with all cars that are recommended to run on premium, but in my experience i could tell when it was on regular. I also don't know if constantly running on regular would do the engine any harm or what harm it would do, but i suspect it wouldn't be good for it in the long term.

 

[MatskiMonk]

Please reply only if you personally have tested!

Depends on what you mean by premium, but I'd run my old E36 328i on 98/99 instead of 95 and just felt everso slightly 'meatier', a little bit smoother, and little bit more pull, but not a huge difference. I now run my E90 320si on 99 but in all honesty I don't notice any difference other than the cost being much higher. It's smaller, higher revving engine, with less power though, so it could just be the percentage difference is similar, but not enough for me to register.

I did once talk to a guy that worked in the industry, and he said in most normal cars you'll notice as much of a difference just by switching brands, as the additives and composition that different brands use in the fuel will vary, some a better than others, some just have characteristics that may suit your use case better than others - different fuels performing differently in summer and winter for instance.

 

[Joey D]

All engines a tuned a specific way. Use the fuel specified in the vehicle's manual. Even the difference between regular and premium is typically $.50 or less, which would make it $8 more to fill up, assuming a 16-gallon tank.

You will notice a difference between ethanol content in fuel, though. The more ethanol, the worse the fuel economy. I try to run E0 as much as possible, as it nets 2-3 more mpg. In addition, E0 is just better for all the components in your fuel system.

 

[wfooshee]

Premium is higher octane, not higher power. The engines that require premium are higher power engines, either by higher compression ratio, forced induction, or other factors such as cams and timing. Running premium in an engine designed for regular may actually give very slightly reduced peak power.

The octane rating of fuel is an indication of its resistance to pre-ignition, not an indicator of energy content. Pre-ignition is when the fuel charge fires before the spark, creating a knock because the piston is still trying to compress the fuel/air mixture and that mixture has ignited, trying to expand. High-compression or forced induction engines require better control of pre-ignition, which is why they require higher-octane fuel. The power comes from the different engine design, not the different fuel; it's the engine that's more powerful, not the fuel. The result is the misconception by many that premium fuel is more powerful. I don't think you necessarily have that misconception, but you did ask the question...

Premium fuel in an engine not requiring it is wasting money. People swear that their car/motorcycle/RV/lawn mower/whatever runs better with it, but that's a self-serving placebo effect they justify themselves with.

That said, some brands of premium fuel might have better detergents and other additives that some folks tell themselves is worthwhile to have.

As for ethanol, while it's true that ethanol reduces the energy content in your fuel slightly, resulting in reduced fuel economy, the added fuel economy of using E0 doesn't come close to reaching the break-even point of its higher price. Modern fuel systems (and "modern" means the last 40 years) have no problem with ethanol. The problem with ethanol is long-term storage because it absorbs water. Treatments like Sta-Bil are easy to come by to combat this, and I use it in my cans I keep for the lawn tractor, and for my generator I would use during power outages after tropical weather, because that fuel may sit for several months before I use it.

 

[Austin plays]

Both really, but unless you are contantly thrashing the engine you feel it more as a slight hesitation in the delivery of power at different throttle imputs. It just doesn't feel quite 'right'.

Think of it as your car is at 100% when using premium. On regular it's not quite the same. I don't know by what percentage it actually makes a difference, or whether its the same with all cars that are recommended to run on premium, but in my experience i could tell when it was on regular. I also don't know if constantly running on regular would do the engine any harm or what harm it would do, but i suspect it wouldn't be good for it in the long term.

Makes sense. Thank you

Depends on what you mean by premium, but I'd run my old E36 328i on 98/99 instead of 95 and just felt everso slightly 'meatier', a little bit smoother, and little bit more pull, but not a huge difference. I now run my E90 320si on 99 but in all honesty I don't notice any difference other than the cost being much higher. It's smaller, higher revving engine, with less power though, so it could just be the percentage difference is similar, but not enough for me to register.

I did once talk to a guy that worked in the industry, and he said in most normal cars you'll notice as much of a difference just by switching brands, as the additives and composition that different brands use in the fuel will vary, some a better than others, some just have characteristics that may suit your use case better than others - different fuels performing differently in summer and winter for instance.

What brand worked better for you??

 

[MatskiMonk]

What brand worked better for you??

Shell's 99 RON was the premium that I noticed most difference with, since they have a bit of a monopoly around where I live that was primarily only against Esso and Gulf standard fuels (95). Obviously if you're in the US things will be entirely different.

I've previously found some research papers online that did chemical composition analysis of various fuels, not much of it meant anything to me, but there clearly were differences in how they went about doing what they did.

 

[Austin plays]

Interesting!! So was it more Shell 99 vs others or even Shell regular vs 99?