Break-In Period
According to a 2005 SAE paper entitled Breaking the Viscosity Paradigm: Formulating Approaches for Optimizing Efficiency and Vehicle Life, ” Concurrent with the strong drive toward better fuel economy, consumers have been demanding increased performance, which has required axle lubricants with enhanced durability protection and lower operating temperatures. There has been a 34% increase in engine horsepower over the last decade, while axle gear sizes have remained constant, sump capacities have been lowered, and drain intervals extended. In the light truck segment there has been a 93% horsepower increase since 1981.”
Most differential wear occurs during the break-in period. Because differentials are not equipped with filters, break-in metals are suspended in the oil, causing increased wear as the particles mesh between the gears. Hauling heavy loads and towing trailers cause additional stress to the differential during the break-in period and can cause premature differential damage. Changing the gear lube after the break-in period (about 5,000 miles) greatly reduces wear and extends differential gear and bearing life. Auto manufacturers are beginning to recognize the importance of drain abrasive break-in materials. Some manufacturers recommend an interval of between 500 and 3,000 miles. The best way to go, is to replace your gear lube with Synthetic Gear Lube.