Break-in oils is for engines with extremely tight and finely fitted plain bearings and piston/liner clearance that is present in modern engines of today. Over head cam engines with strong valve springs and tight valve buckets. Engines that are going to run on long life oils, oils with a large amount of friction reduction additives. Additives that mostly are present in synthetic and semi synthetic oils and sometimes in more expensive mineral oils. 

My personal opinion is that with a normal mineral oil with lesser amount of those expensive additives, the Indian engine will be run in perfectly normal. Add to that, Indian engine does not have the extremely tight and finely fitted plain bearings and piston/liner clearance that is used in modern engines, and the Indian cam rockers are fitted with friction reducing rollers, so there will be no benefit from using a specially blended break-in oil.

No. I try to make it as simple as possible. Because of oils are of such inflamed and opinionated topic, I have to stress that this reply is my personal opinion.

Regarding longevity

The oil consumption system on the 101 does not bring the oil anywhere close to the longevity limits where the quality is of essence. The oil is rapidly consumed or vented out on the road with the 101 engine. The mineral oils commonly available on the shelves are of good enough quality so that the brand differences are not critical. 

Regarding carbon deposits.

However apart from the stock base quality, some oils are depositing more residue and carbon than others, flash point of the oil is one factor of that. But that is a data not commonly shared on the bottle so mainly try and error has to be practised. Pure synthetic oils or blends can show a better result than some plain mineral oils, regarding this. Carbon deposits is a troublesome factor when large piston clearances and poor piston rings are used. Our 101 flateads runs hot and burns oil in the combustion chamber. 

A dollop of a quality 2 stroke oil for air cooled engines, in the petrol tank now and then might keep the carbon at bay because those oils have a detergent additive that infuse the deposits and makes that burn off. Marine, water cooled and snowmobile 2 stroke oils are many times designed for a too cold combustion temperature to be beneficial in our engines. I have heard people run only plain 2 stroke oil in the oil tank, reportedly with no problem.  

Regarding viscosity.

Viscosity does have some importance depending on what clearance is used between the piston and lining. In our flatheads with a piston clearance of .006" or larger, I believe a viscosity of 40 is good to use. A higher viscosity oil is leaving a thicker layer of oil on the surface. The difference is measured in microns, tenths of thousandths of a millimeter. However a thicker oil does not mean the engine runs cooler, it is the other way around because oil is slow at collecting heat!

Roller bearings in the crank, and the cam rollers are not the least better off with high viscosity oils, rather the contrary but the bushings in the cam compartment and gear gaps to a degree benefit from a thicker oil because of the cushion effect a thicker oil will make, mostly for the simple reason of sound emerging. It is the same with sound of piston slap in the cylinder when cold. 

The debate about single vise-versa multi viscosity oils is topics is a non-issue in my opinion if above 10W-X if the pump is so tight it can keep the oil from leak down to the sump. The standard rating of viscosity is complicated, stupid and outdated. I don't go in depth more than say that 15W-50 has the same viscosity as straight 50 oil at 100 deg.C. but flows much easier at 20deg.C

If anything multi viscosity is better just because the oil is always fed cold from the tank to the engine and multi viscosity oil flows lighter when cold. However, the flow in and out of the 101 pump is so slow that it never will cause any cavity or starving issues in summer temperatures even with thick 60-oil. It is different in winter when a much lighter oil has to be used. 

Regarding additives.

Another example is the infected debate about zink additives is a non issue as the Indian engine does not have any friction areas where the amount of ZZDP would be critical. More important is the flash point and film strength/shear stability, but that's going in the pit bog of brands, types and categories of oils.

People regularly bring up the question about detergent/non-detergent oils, but virtually all oils commonly available have additives where the dirt and impurities are kept suspended in the oil. You have to be very specific in searching and finding a non detergent oil today and such an oil is wearing the engine down faster than normal. With our engines without a oil filter of any sorts, the dirt better be suspended and transported out of the engine with the oil.

Yes, load them up with Nickel anti seize. and the exhaust nuts too. 

Oils , I love it, and talk about gas too. Carl-Erik as usual has a great answer.

Jorgen Sundberg at Grevbo Engineering also recommends using a break in additive with an ester component added a capful every fill up of oil, for the first 1500 miles. He builds a lot of motors. 

Actual careful riding is probably the single best way to break a bike in well. Seventies Triumph manuals have very strict guidelines after a ring job. I recently pulled the cylinders off my 28 short frame bobber after the race of gentlemen this year, and they had a mirror glaze on them and no signs of the hone marks left aft maybe 50 to 80 miles of running, but much of that was extremely hard miles. Very little wear, but I will need to break the glaze and rering to run it on the road without oil blowing past the rings.

Gentle throttle, don't lug the engine either, 30-35 miles an hour for a good while, building up slowly and only revving slightly more down hill to start.

Again, Jorgen reckeons 1500 miles before heavy throttle useage, if at all :)

A problem are the brass ferrules both with the T- and Y intakes. They are hard, the tapers require a lot of pressure to conform to the intake, and they are rigid. Over torquing is a common fault that deforms the spouts and may damage the intake nipple rivet in the cylinder! 2 common areas of air leaks.

The ferrules slide on the intakes, one or both sides, when everything contracts and expands with temperature and vibrations so the intake spouts get worn at the contact areas from the ferrules.

The ferrules has to slide or something will crack so it is a good idea to reduce friction as much as possible without compromise sealing. I use Locktite 561 that contains PTFE to lubricate threads and joint. 

To ensure a tight seal spout surfaces and ferrules needs in fact to be pristine without blemishes, clean, smooth and round, ferrules slide-on fit with proper right taper for the nut. Many times intakes are in such bad state that spouts needs to be brazed and turned and the ferrules custom fit. 101 intakes, especially 45ci are very thin.

Cylinders (rather intake nipples) needs to be at as equal height as possible. Only minor height difference should be accepted or else shimmed with base gaskets. And the carburetor should be supported with a bracket.

A better product for the ferrules than brass, is a thermoplastic named PEEK (polyetheretherketone). That require far less nut tightening force than brass to conform, slides with a lot less friction and still seal better. I also lubricate those with 561. However because they are softer they wear on coarse surfaces so better custom fitted rather snug on a turned/polished intake. 

Bubble test is a very valuable diagnostic tool.

Reward is when your 101 is calmly thumping on both cylinders at very low idle.

No, the motor was really only built for the race, I used sport scout cylinders with the small thread plug heads and found the longest reach plugs I could, was actually surprised they seemed fine both flat out and bimbling about on local roads, but the longest run out I had was around 20 odd miles, as bike not very road legal tbh, and I was gunning it a bit then too. 

Was also running a straight 30 oil, which I would not particulalry recommend to anyone, altho there may be a case for very gentle running in with it, but it does have a habit of finding different ways to exit the engine when hot. Indian winter Weight Oil was probabaly around sae30, but that would generally be for temperatures around freezing point. Motor spins A LOT freer with it.