91 octane petrol will ignite at a lower temperature and burn faster, which can cause knocking in an auto engine. Lead compounds were added at one time to raise the octane rating, but recently engines have been redesigned to work on low (<98) octane petrol (or gas in the US colonies)
You should be fine with 91 octane. The higher the octane, the more you engine will like it, but 91 octane is enough for your ES 350.
If vehicle does not "ping" severly on acceleration - no advantage
91-93 octane premium
The 91-octane costs 0.45 riyals per litter and 95-octane is at 0.65 riyals.
This vehicle requires Premium Unleaded. You can try using 89 Octane and see if it pings or not. If it does then you will have to move up to 91 Octane. Do not use Regular, as it will cause pre-detonation and may do harm.
I would use the lower octane unless the vehicle "pings" excessively and if so use the higher octane
The difference between these is 95.
Neither. The Chevy Cruze is designed to run on 87 octane regular fuel. Using a higher octane will provide no benefit whatsoever. No more power and no better mileage. In fact it can cause hard starting. It would be a total waste of money to use anything but 87 octane.
if it is a 2.5 4 cyl 87 octane will be fine. The 3.5 V6 recommends 91 but doesn't require it. If it runs good on 87 then that is what i would use. If not use 91 or higher.
The factors of 91 are 1, 7, 13, 91 The factors of 95 are 1, 5, 19, 95.
Research Octane Number 95
It is a 12.2905% difference.