I just bought a 2002 terramite T5C and want to change hyd oil. How do you drain the tank? In the owners manual they talk about a sump that needs cleaned where is it? The oil they say to use in API SFCD 15W40 is this regular car oil? The only thing I have seen so far is SGCD rating and when I looked on the API web site it said that the SFCD was not used anymore. Any thoughts would be welcomed. big dan