Modern engine design and the need to reduce CO2 emissions have led to the development of additional engine oil categories and a growing number of engine oil viscosity grades for diesel engines. In 2016, the launch of two new diesel engine oil categories (API CK-4 and API FA-4) required shops to accommodate numerous oils properly.


When it comes to the storage and handling of engine oils in a shop, there are some important things to keep in mind to ensure safety and maintain the quality of the oils. The designated storage area for engine oils should be cool, dry, well-ventilated, and away from electrical equipment. Also, avoid storing engine oils near chemicals or substances that may cause contamination. When receiving new shipments of engine oils in drums, bottles, or pails, ensure that all containers are tightly sealed and undamaged before storing them. Damaged containers may lead to oil leakage or contamination. 

Storing oils in a stock room or shop requires some planning:

  • Maintain a well-organized storage system to prevent confusion and ensure proper inventory management. 
  • Arrange the containers in a way that allows for easy access and clear labeling. 
  • Consider using shelves, racks, or storage bins to organize the oils.
  • Avoid cross-contamination by assigning specific storage areas for different grades or types of engine oils to keep them separate.


While engine oils have a reasonably long shelf life, it’s important to rotate your stock to ensure that older oils are used before newer ones. Follow the First-in-First-Out (FIFO) principle by using the oldest stock first to avoid potential degradation of oils due to extended storage periods. In addition, proper storage applies to diesel exhaust fluid (DEF), which has a shelf life of about 18 months if stored in room temperature conditions. Following FIFO is highly recommended for this fluid, as well.


The following tips can help streamline operations and help minimize issues relating to productivity, mixing of different products, and misapplication. 

  • For all oil offerings, dedicate and clearly mark tanks/storage, dispensers, tools, etc., to avoid comingling of different products and misapplication. At a minimum, identify the product name, viscosity grade, and performance level. In this manner, you will also meet weights and measures regulations that have been adopted in over half of the states in the U.S.
  • Reassess your shop’s need for all the oils you stock and eliminate older category oils such as API CJ-4. Older specification oils are unnecessary, thanks to the backward compatibility of current CK-4 oils. Also, evaluate specific viscosity grades and adjust inventory to ensure you stock the proper supply of the most commonly recommended oils for your customer base. 
  • If you plan to change oil product offerings, set a specific date and communicate this information to staff


All service personnel and technicians should know the current diesel oil categories and requirements for each. The API Motor Oil Guide provides current information:

About the Author:

Jeffrey Harmening is senior project manager – EOLCS/DEF with the American Petroleum Institute. If you have questions or need additional information, contact the API Engine Oil Licensing and Certification System at

Modern Contractor Solutions, January 2024
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