Get the lubes inspected from a good mechanic or 3s dealer or better try getting a receipt of the 40K service from the owner to make sure it was done. Ask him where he got the service done from, 3s dealer usually have all the service history.
Don't wash the engine too often. Once in six months is good enough. Only use blower or pressurized air to clean out the dust. If you want to clean the engine like new, get it detailed from some professional.
