Originally Posted by Nos4r2
Odd, seeing as it all comes from the same refineries and storage depots...
Depends what additives have been put in.
I know the "city diesel" can make some cars run lumpy and the Ultra low sulphur fuel isn't great for lubricating pumps etc. On the diesel cars I've had I added a bit of 2 stroke oil as it acts as a cleaner and lubricant, runs quieter too.
Regards supermarket fuel and outboards you'll be fine. Tesco 99 was voted the best fuel for the price although in an outboard I doubt you'd tell any difference.
The super unleaded 97-99 Octane is aimed more at tuned cars where the ECU is mapped for that fuel.