When is Super Unleaded not Super Unleaded?

[Rockall]

On a remote Scottish island, where we've never had anything other than 95 Octane fuel, one of our local Fuel Stations announced that they were to start stocking 98 Octane Super Unleaded.

Great, I thought, and started using the new fuel in my S1. After a couple of months, I started to notice a misfire under heavy load and, as a last resort in the diagnostic procedure, decided to replace the Spark Plugs.

Turns out that our local retailer was actually stocking 95 Octane regular Unleaded and adding a (red) Octane Booster of his own at a 7p per litre premium - look at how red the plug tips are. One £65 set of plugs later and everything's sorted. And it's back to 95 ron for me!

 

[Retroman]

They look rather black and sooty as if either the car is over fuelling or not fully burning the fuel being supplied - normally the premium fuel additives result in a cleaner burn so god knows what this retailer was adding???

 

[SPIKE_]

"Trade Description Act" springs to mind! That really does sound like a nightmare, but lucky you got to the bottom of the issue pretty quickly.