Diesel Engine Oil Selection and Maintenance Guidelines

Maintenance is often overlooked when using diesel engines, and the most critical aspect of maintenance is oil replacement. This process requires selecting oil with appropriate viscosity based on temperature conditions. Dingbo Power Generator Manufacturer explains the details below to help you understand thoroughly.

Proper selection of diesel engine oil is crucial for ensuring the engine’s performance and lifespan. In summary, the main functions of oil in a diesel engine include lubrication, cooling, cleaning, vibration reduction, and sealing. In diesel engines equipped with HVT (Hydraulic Variable Timing) and STC (Step Timing Control), oil also serves as a hydraulic medium. The quality of oil can be reflected through key inspection indicators such as viscosity, pour point, oxidation stability, and acidity/alkalinity (TAN and TBN).

1. Viscosity Grade Selection

Under the SAE standard, oil viscosity is classified into single-grade and multi-grade. Using multi-grade oil reduces deposit formation, improves cold-start performance, and enhances engine durability by ensuring lubrication under high temperatures.

Recommended for normal ambient temperatures (above -15°C): SAE 15W/40. Practice has shown that multi-grade oil significantly reduces fuel consumption compared to single-grade oil under low engine loads.

Low-temperature conditions: Lower-viscosity multi-grade oil may be used temporarily, but SAE 15W/40 should be resumed once temperatures rise.

Extreme cold (constant -25°C or below): API Category III synthetic oil is recommended. For temperatures above -25°C, mineral-based multi-grade oil is advised.

Permanently cold environments (never exceeding 0°C): API Category III 0W/30 synthetic oil is suitable.

Note: Single-grade oil is not recommended. If multi-grade oil is unavailable, single-grade oil may be used as a temporary substitute, but it may cause poor lubrication during cold starts/low loads, increased fuel consumption, or insufficient viscosity under high loads. Special "break-in" oil is not recommended for new or overhauled engines.

2. Quality Grade Specifications

Use oil meeting API performance grade CF-4 or higher. If CF-4 oil is unavailable:

on-electronic injection engines without emission requirements may use CD-grade oil, but oil change intervals must be shortened.

Oils below CD grade are strictly prohibited.

3. Synthetic Oil

Synthetic oil is designed for extreme cold environments (as low as -45°C), where petroleum-based oil performs poorly. It is recommended for constant temperatures below -25°C. All synthetic oils must meet API Category III and appropriate SAE viscosity grades.

Guangxi Dingbo Power Equipment Manufacturing Co.,Ltd was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. The company has a registered capital of 218.88 million yuan. The company covers an area of 86,000 square meters and a building area of 55,000 square meters. There are more than 660 employees, including 456 professional technicians and 106 senior technicians. It has 46 sales and service outlets nationwide. The main products are diesel engines, generator sets, and diesel generators, providing users with a one-stop service of design, supply, debugging and maintenance at any time. Dingbo has always insisted on using first-class talents, building first-class enterprises, manufacturing first-class products, creating first-class services, and making every effort to build a first-class domestic enterprise. If any question please feel free to visit our website https://www.dieselgeneratortech.com/ or send email to [email protected].