HD 50

The HD 50 API CI-4 is a heavy-duty monograde diesel engine oil, formulated to operate under extreme load, temperature, and mechanical stress conditions. Its SAE 50 viscosity provides a very resistant lubricating film at high temperatures, making it especially suitable for older or intermediate generation engines operating in warm climates or with high wear.

The API CI-4 specification, developed by the American Petroleum Institute, is designed for diesel engines equipped with exhaust gas recirculation (EGR) systems, offering superior soot control, excellent wear protection, and high internal cleaning capacity. This category clearly surpasses previous classifications such as API CH-4 and CF-4, although in newer engines it has been replaced by standards like API CK-4.

In some cases, the oil may carry the CI-4/SL designation, indicating that it also meets the old API SL specification for gasoline engines, expanding its application field as a universal lubricant when permitted by the manufacturer.