Wastes money.
is safer for the environment
Using an octane rated lower than your vehicle specification will damage the engine. I would recommend not doing that.
Use the lowest octane that does not 'ping' (detonation). The higher octane is not only more expensive, it can, in some cases, cost you performance. Its got to do with things like the latent heat of vaporization and other scientific formulas.
Using octane fuel higher than your car is rated generally has minimal impact on performance or efficiency. Most modern engines are designed to run optimally on the recommended octane level, and using a higher octane fuel may not provide any noticeable benefits. However, it can help prevent knocking in high-performance or modified engines that require higher octane. In most cases, it's an unnecessary expense without significant advantages for standard vehicles.
No. * Added - Unless you are prepared to modify the tuning of your engine, the recommended octane rating is the best. Higher octanes do not provide more power, they simply burn slower. The higher the octane, the harder it is to ignite, which in most cases, will have no effect, but can make make the car harder to start. If you have an older car and have the equipment to adjust your vehicles system, using a higher octane fuel can result in higher gas mileage and more power. It requires that the spark timing be advanced to begin burning slightly sooner - and if a lower octane is then used with the same set-up, it can destroy the engine.
If vehicle does not "ping" severly on acceleration - no advantage
Yes, you can mix 87 octane gasoline with 93 octane gasoline without any issues. The resulting octane rating will be somewhere between the two, depending on the proportions mixed. However, using a higher octane fuel than required for your vehicle may not provide any additional benefits in terms of performance or efficiency. Always refer to your vehicle's owner manual for the recommended fuel octane rating.
A 3vze engine will take anywhere from regular 87 octane, up to 100 octane race gas. However what is your purpose to using higher or lower octane, Using regular, plus, or premium will work well. however higher mile engines would prefer 91 octane!
From the owner's manual: "If your vehicle has the 4.6L V8 engine (VIN Code Y), use premium unleaded gasoline with a posted octane rating of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but your vehicle's acceleration could be slightly reduced, and you might notice a slight audible knocking noise, commonly referred to as spark knock." So you can use either regular, mid-grade, or premium. I have not noticed any loss of acceleration or spark knock by using 87 octane fuel.
It can, ultimately. It will ruin the plugs and valves, the compression ratio will not be correct, thermal transfer will be to high. The timing will be wrong. It will not be efficient. The small amount of extra HP is not worth the expence when it goes wrong
87 octane regular is recommended. Using a higher octane is a total waste of money and will provide no benefits whatsoever.
Per the owners manual 91 octane fuel (premium) is recommended. Using a lower octane decrease the performance of the vehicle.