"I had a Kleen Oil bypass filter system on my Detroit Diesel. Last summer at the Fergus Truck Show, I replace it with a Eco-Tek/RRR one and put Eco-Tek additives in. I checked the oil after about a week and I thought there was no oil in the engine.- it was so clean. Usually it was black by this time. I also couldn't believe how well it was running - smoother, quieter, less smoke and more powerful".