For the 2015 model year, the Mercedes-Benz C-class owners' manual provides the vehicle's oil change specifications. Customers can download copies of their vehicles' owners' manuals on the Mercedes website. Mercedes does not recommend a particular viscosity of oil, only that customers choose one appropriate for their regions' temperature ranges.
The 2015 Mercedes Benz C300 must use oil that adheres to the company's 229.3, 229.5, 229.51 or 229.52 oil-quality specifications. The 2015 C400's oil must adhere to the 229.5 specification. On its website, Mercedes provides a list of compliant oils. They are manufactured by companies such as Mobile, Castrol, Pennzoil, Valvoline and Shell.