Johnny, whether you got good results using 5W20, or canola oil, or Three-in-One oil in your BMW doesn't make it a logical choice in an airhead. Oak Okleshen and Robert Fleischer know more about air-cooled BMW engines and the oil they like infinitely better than you or I and they both recommend 20W-50 at all times unless riding in below freezing temperatures. That's more than good enough for me.
Here' a quote from Fleischer:
"For Airheads, due to the variability of some heat-treated parts, and due to the type of cam and followers; I recommend the following oils:
(1) Mobil 1 V-Twin in 20W50 grade. You can usually extend the drain intervals due to this being a full synthetic oil. This oil can be a little pricey, but drain intervals, assuming longer touring miles than city traffic miles, could be quite long, with safety. This oil has plenty of ZDDP in it, and is a good formulation, in all respects.
(2) Golden Spectro 4 in 20W50...can also have SOMEwhat of extended drain intervals, as it is a part-synthetic and I have considerable experience with using this oil. This oil is a bit expensive, but is of excellent quality. It is a toss-up between (1) and (2), as to which you should buy.
(3) BMW 20W50 NON-synthetic motorcycle oil. This is a good oil, but not quite as good as the above oils.
All the above oils have goodly high quantities of ZDDP in them, and the base oils are of good quality.
(4) Valvoline 4-stroke motorcycle oil, in 20W50 (or 10W40 for freezing cold areas). Not as good as (1) through (3) but OK.
The above oils will especially pay for their cost, over the long run, if you keep the bike a long time and for high mileage. Do NOT use cheap energy saving (so marked, and probably have starburst symbol) car oils, and particularly not in 5W20, 5W30, 10W30, 10W40. If you make ONLY short trips (under 8 or 10 miles), change your oil every 4 months. If you ride now and then for over 20 miles at one time, you might be able to extend the changes to 6 months...or even a year. The Euro specification that is tighter and more strict than what is in the USA, is ACEA-A3. Look for it on some products in the USA nowadays. Do NOT use oils with the energy-saving Starburst logo. Do NOT use the latest CJ-4 oil, as it is only so-so for our bikes. Remember, if you use synthetics, that they are NOT all the same! Be SURE yours has ZDDP, and a goodly amount, for your Airhead. I cannot recommend Castrol motor oils, of ANY type. If you ride in rather cold weather, below freezing, I suggest a lighter grade than 20W50. 10W40 perhaps.