The function of a vehicle’s differential is to transmit engine power to the wheels, while allowing them to rotate at different speeds.

   Differential design has evolved greatly since its conception.  The first differential is thought to have been an early clockwork mechanism

of Greek origin, and it can be traced back to around 87 B.C.  The lubrication used for these gears is unknown, but because a lubricant of

any kind may have changed the clock’s timing, it is speculated that no lubricant was used.  Most all branches of engineering owe something to clock making.  For example, the thermostat in an oven, the chain drive of a dredger and the differential gear in the axle of a car were all first invented for clockwork.

   Wooden cylindrical peg type gears lubricated with animal fat were used around 1200 A.D. for ship anchor hoists and catapult pre-tensioning.  In 1827 Onesime Pecqueur of France installed the first differential gearing into a steam-powered machine.  Pecqueur also invented and patented the first limited slip type axle.  In 1870 James Starley, known as the father of the British bicycle industry, invented a tricycle with a differential gear, and the principle was used as the basis for the automotive differential.  Automotive differentials incorporated worm drive gear sets lubricated with heavy petroleum oil until Packard introduced the modern hypoid differential in 1925.

   The worm drive differentials used in early automobiles were unreliable and noisy.  The introduction of hypoid gears solved  the noise problem, but their sliding action increased wear.  In order to extend gear life, lead-type extreme pressure (EP) additives were developed and added to gear lubes in 1930. However, because lead was determined to cause health problems, the lead-type EP additives were replaced by sulfur phosphorus EP additives in the 1950’s.  The sulfur phosphorus additives provided improved benefits and are still in use today.

1) Less lubricant used

2) Up to 93 percent more horsepower

3) Towing limits increased from 7,500 to 18,000 lbs.

4) Air flow for cooling decreased in favor of increased

aerodynamics

5) Smog systems require hotter running engines,

generating increased air temperatures around the

differential

6) Increased differential temperatures up to 300°F

7) Increased interior room sacrifices air space for cooling

around the differential

8) Exhaust pipes and mufflers pushed closer to the differential,

increasing heat.

   AMSOIL Synthetic Gear Lubes are specifically formulated to address modern differential operating conditions, providing extended drain intervals, long differential gear and bearing life and peace of mind.

   New differentials go through a break-in period and should have the break-in gear lube changed after the first 5,000 miles to assure differential integrity over the life of the vehicle.  AMSOIL Synthetic Gear Lubes provide superior protection and performance for differentials