API CK-4, API FA-4: Overview of the API specification change

The American Petroleum Institute’s (API) heavy-duty diesel engine oil category (commonly referred to API CK-4, API FA-4) is designed to help reduce emissions and boost fuel economy. Imperial Oil wants you to be prepared for this industrywide change. Get all of the key facts below.

What is API CK-4, API FA-4 all about?

The development of an oil category

API CK-4, API FA-4 products

API CK-4, API FA-4 established two diesel engine oil specifications – one with backward compatibility for older engine technology (“CK-4”) and one for use with newer engine technology (“FA-4”).
For FA-4, the aim is to reduce greenhouse gas emissions and improve fuel efficiency. CK-4 oils are designed as direct replacements to current CJ-4 oils, offering enhancements in oxidation resistance, shear stability and aeration control.

How does API CK-4, API FA-4 affect owner-operators and fleets?

Switching engine oils

Truck driver standing outside truck

API CK-4, API FA-4 does not change the best practices that help drive the success of owner-operators and fleets. It’s also important to note that API CK-4, API FA-4 does not affect every business in the same way.

Some owner-operators and fleets with older equipment may see only a small impact from API CK-4, API FA-4 – switching from CJ-4 oils to the enhanced CK-4 oils. In comparison, fleets with a combination of older and newer equipment may choose to stock both CK-4 and FA-4 oils until the older units are cycled out of the fleet.

Owner-operators and fleets operating newer equipment with advanced engine technology should follow original equipment manufacturer recommendations.

When does API CK-4, API FA-4 arrive?


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API CK-4, API FA-4 diesel engine oils are in market.

Where has API CK-4, API FA-4 been applied?

North America

PC11 North America map

API CK-4, API FA-4 has a global impact, but the primary applications are in the United States, Canada and Mexico.

Why do we need a new oil specification?

Emissions and fuel efficiency standards

Yellow fuel gauge icon

Changing industry standards call for vehicle and engine improvements capable of:

  • Reducing carbon dioxide and greenhouse gas emissions
  • Enhancing fuel efficiency
  • Maintaining engine durability while improving oxidation resistance, shear stability and aeration control

These improved engine designs require commercial vehicle engine oils with performance capabilities far exceeding those of CJ-4 oils.

How were the two new oils created?

Research, development and testing

Beaker in lab close up

API CK-4, API FA-4 diesel engine oils have gone through substantial research and development, ensuring the lubricant technology meets new performance targets while improving engine wear protection. After being proven via extensive field testing, API CK-4, API FA-4 Mobil Delvac™ engine oils were announced in September 2016.

As of June 2017, we have accumulated more than 80 million kilometres of testing data on our CK-4 and FA-4 formulations. We are also now accumulating more than 2.4 million kilometres a month of additional testing data with select fleet partners. Our current field testing includes about 200 trucks.

  • API CK-4, API FA-4 products

    The new Mobil Delvac diesel engine oils will help on- and off-highway fleets, fleet managers and owner/operators reach their business goals.

  • PC-11

    Get more of the story behind API CK-4, API FA-4. Plus, learn how the new CK-4 and FA-4 oils can help your business.

  • PC-11

    There are a lot of questions surrounding the new diesel engine oil specification change. Get more of the details behind API CK-4, API FA-4 here.