What causes engine sludge deposits?
The popular idea is that when gasoline is burned in engines, it’s changed to harmless gases which blow out the exhaust pipe. Unfortunately this is not the case. For every 100 gallons of gasoline burned in an engine (every 1,200 to 2,000 miles in passenger cars), the following things are formed in addition to exhaust gases: • 90-120 gallons of water • 3 to 10 gallons of unburned gasoline • ½ to 2 pounds of soot • ¼ to 1 pound of resins and varnishes • 1 to 4 pounds of nitrogen and sulfur acids • 6 to 10 ounces of insoluble lead salts (if leaded gasoline is used) • 1 to 2 ounces of hydrochloric and hydrobromic acids Notice the large amounts and the variety of things formed from the burning of only 100 gallons of gasoline, besides mere exhaust gases. When an engine is good and warm from steady running, these various combustion products are mostly blown out the exhaust, so they cause little or no trouble. But when an engine is cold, due to frequent stopping, standing and starting, the cool
