Here's a lube chart for your M. Arrows point to check, drain, and fill/grease points, and capacities.
A correction to the above mentioned fill point. On the H's & M's, there is a winged fill cap on the right side of the engine, at the front of the distributor drive. I've attached a pic of one on an H, but same location. All I've had/seen have a perforated piece of metal, to keep items from dropping into the timing gears. I'm sure some have been removed on some. If oil is poured in too quick, it can overflow. We have a 5 qt. oil can with a trigger that empty's pretty quick, and have had it do that, pouring in 30wt. in cooler weather. Out of quart bottles, probably not a worry, but thought I'd give you a heads up. Most of the time, once I start filling out of whatever, I'll put the opening of the bottle, or pour spout over the stud sticking up the cap screws down on, to slow the oil out of the container.
Click on the pic of the lube chart to enlarge. Right click on it, to print, and when it print's out, it will be a full size page print out.
Hope this helps..!!