Oil Appearance

WARNING: This page is about a different car, the 2019 Nissan NV3500 HD, 2019 Nissan NV2500 HD, and 2019 Nissan NV1500. However, it is still accessible from the selected car via links, so may be relevant.

Check the engine oil for a white, milky appearance or excessive contamination.
If the engine oil is milky, it is highly probable that it is contaminated with engine coolant. Repair or replace damaged parts.