Hello Chris,
Its vital you keep the correct oil level in the crankcase. You will need to check often to determine if the oil pump is metering the right makeup amount for your consumption (loss) which is affected by your riding style (speed, acceleration, revving) and land grades. The R&O book will explain how to adjust the pump.
I typically make short fun runs, like 20-30 miles as often as I can and on average once a week. Even though that is not much my ALWAYS return routine is to check the sump oil level while the oil is hot (hot makes for a fast check). I like to see a little excess come out. If nothing comes out I open the front valve that comes from the hand pump until some does come out, then I close up leaving a little excess in there. The pumps on both my 101's leak with the oil stopped by that valve so I never need to pump. If I was riding particularly fast I may, while out, open that valve for maybe 20 seconds to leak in some extra oil.
If a 101 has been sitting for like a month or more (during deep winter) I always drain any excess oil from the sump that may have leaked in it. You will have to come to know your bike as leaking into the sump may happen more often.
Check the primary level (includes transmission) but less often is needed.
I installed brass thumb screw bleeder valves on the sumps and primaries of both my 101's for fast bleeding. I would have to look up what I use and where I got them. But the thumb screws loosen from vibrations so they need a snug with pliers when closing.
Nothing I like better that an "oil thread" and I have spent much of the 12 years of my time with old Indian motorcycles reading thoroughly about oils. My conclusion IMO: it doesn't much matter what you use with these old engines, except:
(1) To prevent slipping of the wet clutch the oil must be rated JASO MA or JASO MA2 (this will be on the container, at least in the US.)
(2) 50 wt. for engine, primary/clutch and transmission is common but since the primary and transmission are separate from the engine and share their oil, using a lower viscosity there, as low as 30, will prevent much spinning of the plates when trying to engage a gear. And if you ride in heat and cold use a multi-grade.
I have accumulated many oil types and brands and have just used up what I collected so I get quite a mix in the tank. Because I ride in summer and winter and mostly in mild cold and also I have come to keep things simple, I now just use Castrol GO 4t 10w40 motorcycle oil in engine and primary/trans and in all my scouts. IMO the brand doesn't matter.
