Used to get the Wilko low ash stuff irrc, was cheap and helped quieten them a bit.
Adding Biodiesel really helped shut them up, could defiantly tell the difference in noise when I was back to just using pump diesel
However biodiesel is one of this risky things that some say the CR system doesn't like it as it's too thick. I used it for 2 years and had nothing explode on me, just a clogged FPR which was fixed with a quick blast of wd40. However this may not be the case for everyone so dont just assume bio is a-okay
Adding Biodiesel really helped shut them up, could defiantly tell the difference in noise when I was back to just using pump diesel
However biodiesel is one of this risky things that some say the CR system doesn't like it as it's too thick. I used it for 2 years and had nothing explode on me, just a clogged FPR which was fixed with a quick blast of wd40. However this may not be the case for everyone so dont just assume bio is a-okay