Break In Oil, Which one & Type?

You will be o.k. using a regular 2 stroke oil for break in...I don't know if Havoline 2 Cycle TCW-3 is synthetic or regular though.
I would switch to a synthetic like Mobile MX4t as soon as break in is complete...Personally, especially on the 2 stroke my feeling that using a regular oil for break in isn't that critical if you don't baby it....

If you ride it too slow and let it build up too much heat you can cause cylinder wall glazing when using a synthetic....However, by limiting your riding time to about 10 minutes per session for a total of 1 hour for break in, allowing complete cool downs after each session, and doing a few brief full throttle runs in the lower gears during each session you can avoid the glazing and get a good ring seat....I would recommend this with a regular oil as well...

I consider the "no synthetic oil for break in" advice to be an urban legend. 2 strokes in particular will seat piston rings very quickly. There is no oil that I know of that will prevent the normal and typical metal to metal wear experienced in the internal combustion engine.

To bolster my point I can point out the various automobile manufacturers that produce new cars with synthetic oil installed at the factory. In addition, I have never seen evidence that synthetic oil will reduce the internal wear rate vs. quality petroleum oil. That is especially true for 2 stroke engines.

Chris