STP® Smoke Treatment is designed for petrol engines to provide a thick oil cushion to help fill gaps, created between the cylinder walls, piston rings valve guide seats on worn engines and reduce oil blow-by and smoking. STP® Smoke Treatment reduces exhaust smoke and engine noise, lowers oil consumption and protects against engine wear. STP® Smoke Treatment may also be used in diesel engines, if it has been determined that the oil is burning the cause of excessive exhaust smoke.