Yep, I think my drain plug is 13mm as well. Altough when I use a rachet I need the 3" extention to get to the drain plug and still have a decent amount of 'swing'.

One recomendation I rec'd on this forum is to take the plunge and get a Torque Wrench. The MB CD-Rom Manual specifies tightening torques for almost every bolt. On my engine (617.912) the tightening torque for the drain plug is 40 Nm and the Tightening Nuts on the oil filter cover are 20-25 Nm. Tightening the drain plug with the torque wrench can be a little tight on space, but it is possible.

Its a pricy hand tool, but offers some solice in knowing your bolts are tightend to spec.

Have fun, changing the oil is one of my favorite 'auto-pilot' tasks.

I will reiterate what has been said here thousands of times
"Change it hot, and change it often"

__________________
James

85 300SD 285k
Charcoal Gray/Grey MB-Tex

79 300CD 142000mi "Rabenshwarz"
Black / Black MB-Tex, Burlwood Int. TOTALLED - 10/24/02 --