AMSOIL Technical Service Bulletin: Gear Oil Thermal Runaway
AMSOIL has released a technical service bulletin on a condition known as “Thermal Runaway”. The AMSOIL Technical Service Bulletin on Gear Oil Thermal Runaway describes the condition as:
“The extreme loads, pressures and temperatures experienced by modern vehicles place increased stress on gear lubricants that can lead to a serious condition known as thermal runaway. As temperatures in the differential climb upward, gear lubricants tend to lose viscosity, while extreme loads and pressures can break the lubricant film, causing increased metal-to-metal contact and heat. The increased friction and heat, in turn, cause the lubricant to lose further viscosity, which further increases friction and heat. As friction and heat increase, lubricant viscosity decreases. As viscosity decreases, friction and heat continue to spiral upward. The hotter it gets, the hotter it gets. It is a vicious cycle that eventually leads to greatly increased wear and irreparable equipment damage.”
Also noted is how diesel pickup horsepower ratings have risen by 34% in the last decade and by 91% since 1981! Towing capacities have risen commensurately placing unprecedented stress on differentials. Obviously your father’s gear lube is not going to cut it anyone. The bulletin also describes how installing the correct grade of AMSOIL Synthetic Gear Lube can prevent thermal runaway due to its superior ability resist breakdown and to stay in the proper viscosity grade. Then things get really interesting as AMSOIL SEVERE GEAR® Synthetic 75W-90 is put through the “KRL 20-Hour Shear Test”. This an “SAE required test for all automotive gear lubes. This specification requires that gear lubes not shear down and fall below the minimum viscosity for that grade.” Once again AMSOIL “names names” as gear lubes from Pennzoil, Mopar, GM, Royal Purple and Torco are also tested and compared.
