Oh yes - it is still a Diesel Engine - even though it's running on "Heavy Fuel".
As already mentioned - some start them on Diesel and switch over to Heavy Fuel, after the Engine has warmed up ....
I will not claim to know much about the subject - like I haven't got a clue about how they manage to stop one of the Cylinders for maintanace - while the rest of the Engine keeps running ....

This can be done as it is WAY to Expensive, to stop the Ship from sailing during Maintenance ....
So a Service Crew is send out with a helicopter and stays on board for like 3 months while they do a complete Engine Overhaul .... and the Ship is still operating as normal all this time ....
Per
