LSPI stands for low-speed pre-ignition, a severe engine knocking phenomenon that occurs in turbocharged direct-injection gasoline engines operating at low speeds and high loads. It is often triggered by droplets of engine oil or fuel-oil mixtures in the cylinder auto-igniting before the spark plug fires. This creates massive cylinder pressure spikes that can crack pistons and bend connecting rods.
We had to switch to the new API SP oil because the old formulation was causing LSPI and destroying pistons in the fleet.
Lubricant formulators discovered that high levels of calcium detergents increase the risk of LSPI, leading to the development of magnesium-based additive packages to mitigate the problem.
Related terms
API donut
The circular label on motor oil containers that displays its performance standards and viscosity.
Additive package
Pre-blended mix of performance chemicals that a blender adds to base oil to make a finished lubricant.
Calcium sulfonate
Grease thickener based on overbased calcium sulfonate, known for water resistance and built-in EP protection.