The supplier of the fluids and lubricants is responsible for the worldwide standard quality of their products.

The MTU requirements for approval of engine oils for diesel engines are contained in the MTU Factory Standards MTL 5044 and MTL 5051 for first-use oils and corrosion-inhibiting oils.

For gas engines, oil approval requirements are contained in MTU Factory Standard MTL 5074 and for two-cycle engines in MTL 5111.

These standards can be ordered under these reference numbers. Manufacturers of engine oils are notified in writing if their product is approved.

Approved diesel engine oils are divided into the following MTU Quality Categories:

• Oil Category 1: Standard quality / Single and multigrade oils
• Oil Category 2: Higher quality / Single and multigrade oils
• Oil Category 2.1: Multigrade oils with a low ash-forming additive content (low SAPS oils)
• Oil Category 3: Highest quality / Multigrade oils
• Oil Category 3.1: Multigrade oils with a low ash-forming additive content (low SAPS oils)

Low SAPS oils are oils with a low sulfur and phosphor content and an ash-forming additive content of ≤1%. They are only approved if the sulfur content in the fuel does not exceed 50 mg/kg. When using diesel particle filters, it is advisable to use these oils to avoid fast coating of the filter with ash particles. Selection of a suitable engine oil is based on fuel quality, projected oil drain interval, and on-site climatic conditions.

At present there is no international industrial standard that alone takes into account all these criteria.