Oil drain plug on Mercedes-Benz MBE 906
I was changing the oil on our 2008 Gulfstream 40 UL with the Mercedes-Benz MBE 906 this afternoon and have a question for those of you more experienced with heavy Diesel engines.
There is a drain plug in the middle of the oil pan on a slanted face. It took a 10mm hex and was what I expected to see. I drained the oil, but came up about 3/4 of a gallon short of what I thought I'd have.
In looking at the plug location, there's a significant portion of the oil pan that's about 3/4 of an inch below the bottom edge of the oil drain hole. Grrrr.
There's also another plug at the back of the oil pan that's not referenced in any of the Mercedes-Benz documentation (at least that I can find). It's a much larger plug that's about an inch and a half across and looks like it would take a 14 or 15mm Hex. The plug itself also appears to be aluminum instead of steel.
I didn't have a Hex that size with me and needed to move the coach, so I just left the remaining oil and filled it up.
In the future, I'd sure like to drain the entire pan. Is that what the large plug is for? Any idea why the service manuals reference using the smaller plug for oil changes, even though it leaves oil in the pan?
Thank you, in advance, for your time and knowledge!
2008 Gulf Stream Yellowstone 40UL