I have been having some trouble with sludge in my diesel fleet and the oil manufacturer being Citgo says all of my trucks have a high soot level causing the oil sludge . I have lost 2 engines already out of 30 plus on the road. The oil they were selling me in bulk was bad to foam and even looked milky or cloudy. I have since switched to Mobile delvac 1300 plus and my engines are cleaning up nicely and none of them are EGR engines. I dont feel that with the fleet of trucks averaging at most a gallon of oil per week that the soot is the problem like they say. I feel that it something they Citgo and there engineers are not telling me. does anyone have any ideas on this.