Would diesel harmful to E270 CDI engine?

No, diesel fuel is not harmful to the E270 CDI engine. The E270 CDI is a Mercedes-Benz diesel engine that is specifically designed to run on diesel fuel. Diesel fuel is a type of fuel that is derived from crude oil and is commonly used in compression-ignition engines, such as those found in cars, trucks, and buses. The E270 CDI engine is a modern and efficient diesel engine that meets all current emission standards. It is a reliable and fuel-efficient engine that is well-suited for everyday use.