In a recent thread the topic of engine oil thinning and how this affects getting into neutral when stationary was discussed. See the comments by TM regarding clutch performance and Bob Kelly III regarding multigrade oil degradation:
https://thexscafedotcom.wordpress.com/2012/02/13/xs650-hall-on-oil/
If you use a 10w type multigrade oil then the oil will thin towards a lower value than if you were to use a 20w type. The result is that after many miles the oil viscosity may be getting lower for the 10W types so lubrication may be suffering more than if the 20W type were used. The key to XS oil use has got to be changing it regularly. I do not know when the Mobil-1 extended life 10W60 was being changed - probably at about 1000 miles is my guess. People are suggesting 1000 - 1500 miles but based on TM's comments in the above link regarding clutch performance it seems 1000 miles is the better time to change the oil.
Perhaps you should just go for a 20W-50 motorcycle oil. The following link to "thexscafedotcom" gives a Tony Hall article:
https://thexscafedotcom.wordpress.com/category/m-engine/motor-oil/
Edit (11/03/21): Link to Tony Hall article will not work. Instead type Tony Hall into the search facility at top left of page.
Although this covers several topics to do with lubrication/filters/cooler, in the last half of the second column he speaks about oil and suggests not to go thinner and when best to change oil versus regular or infrequent running.
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I just read the Tony Hall oil thing again and it dawned on me that he mentioned most high mileage bikes have had frequent oil changes. Well....
I bought the old 72 at about 4K miles and didn't do the top end until about 80 to 85k miles. I've only changed the oil at 2,000 miles +/- 100 miles at least in the last 11 years since I put it on the road again. When I bought it in 76, I was 25. I'm sure I easily surpassed 2k miles in my endeavors. Maybe up to 3K. I do remember it not shifting into neutral very well in the summer. I will admit, when the shifting became difficult, I did change the oil. Well it was in NJ, so it wasn't super hot.
Important to note, I only used Castrol 20W-50, and sometimes Castro HM 20W50. I still only change it at 2K miles. It's a solid bike! Since I installed the 750 kit, I've been using all kinds of oil. I mentioned Castrol 10W-60, but at the time, (2018) it was $16/qt. I have no fookin idea what it costs now & I don't care, I ain't buying it. I sometimes use Mobil 1, 15W50, (it has extra ZDDP in it), and sometimes Walmart 20W-50 mineral, and sometimes Mobil 1, 20W-50, motorcycle Twin oil. Also expensive. I may just go back to Castrol 20W-50 mineral in the summer and 10W40 in the winter, with some ZDDP additive.
What it boils down to is, without a real oil filter, it doesn't matter what kind of oil you use, you still have to change the XS oil at at least 2000 miles.
Note: My Virago XV750 has a a real oil filter and the book says change the oil at 4K miles. At 4K, the oil is about as dirty as the XS at 2K miles. I change my Virago at about 3K religously, and the filters are cheap.
