Just run a tank of vortex diesel, not convinced on the economy, it did run a little quieter the next day after driving home 15 Klm and when fuelled up this week with standard diesel getting 15.3 ltr/100klm (4.2td, 33" mud tyres, 2" lift ) got 16.5 on vortex same driving conditions but aircon was on with standard fuel go figure and cost 10cents a litre more ouch! I think I'll be buying the additive to put in my fuel.