Tuesday, Jun 16, 2020 at 10:24
I dunno , if the manufacturer specifies 91 and it knocks / pings , I would be asking why .
You bought a car that's supposed to operate on 91oct , you shouldn't have to use the more expensive fuel .
If the motor has done a lot of K's , I can understand it might have a carbon build up on the top of the pistons or in the combustion chamber , increasing the compression .
Most new motors should have knock sensors that should stop it knocking , still not a good idea to use a lower octane fuel than recommended .
There are some Y62 owners that use nothing but 91 or even E10 / 94 oct and have no problems the specs say 95 or higher , 98 for best performance .
Like I said I have used 91 in my Y62 when I had no other choice and haven't noticed any difference .
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