Finished first tank of Shell diesel with Diesel Rhino additive and noticed no difference at all with MPG. Not sure if it's really running any better either, still triggering limp mode in 4th occasionally but I think I've changed my driving rather than the additive helping out there. I'll see if anything changes as I use up the bottle with each refuelling (10 treatments altogether I think). As for the limp mode I'll be doing the Mr Muscle trick again (worked last time) and make sure the actuator is still moving freely next time I'm under the car.