I’ve heard that if you use good quality fuel, then your engine won’t develop soot build-up. Is this true?
That is incorrect! ALL engines that have an EGR valve WILL develop a build-up of soot (carbon). Although continuous use of diesel additives/conditioners or using very high-quality diesel fuel can lessen the effect of soot build-up, it will unfortunately NOT stop it. We have seen soot contamination as early as 30,000ks (this was in an MQ Triton), however it does vary depending on driving conditions & also the engine (some develop carbon build-up quicker/more so than others).
We have found that city-driven, short trip stop-start vehicles will develop soot contamination quicker than predominantly highway driven vehicles or “harder driven” vehicles. All in all, if you have an EGR valve, then it WILL develop soot!