On my 93 Ranger 4.0L, I have to run 91 octane shell to prevent pinging. on shell 87 it's very noticable.
With any other gasoline, even Arco, it's fine on 87.
Motor has Motorcraft OE double platnum fine wire plugs.
Gas additive added twice during oil run.
I've never had good results with shell gas. I know it's not the gas, but the addtive package.
I've always noticed shell gas is ALWAYS higher than the other name brand gasolines.
So to me. why pay more for getting less?
Where I live, gas comes from the same place.. just depends on the additve they put in when they fill it.
Techron used to be ONLY in the 92 octane fuel, now it's in all blends of chevron gas.
I tell people you get more techron out of the bottle vs. a tank of fuel.
Sorry shell... lower your prices.