next time, use ARX for cleaning, equally, if not more effective, and much safer on the engine... (helps seals, rather than hurts them like seafoam)... Auto-RX.com
as for oil viscosity... I was reading the results of a recent test done at a university. They measured engine wear by introducing some number of radiactive particals into the engine, then using an imager of sorts to measure the wear of the metal. (easier than tearing down an engine and micing everything).. What they found, was that the majority of engine wear occurs while the oil is still thick during warmup, after the oil is up to temp and flowing at optimal speeds, the wear slows down drastically. I recall something like 100 nanometers within the first 20 minuts on "thick, cold" oil, and then 5 nanometers of wear per hour of run time thereafter.
The point being, that the faster you get the flow up to speed, the better. Thicker oil will always flow a bit slower, and will take longer to flow as fast as a thinner oil during warmup...
So, even in warm climates, the lowest "W" rating possible is actually best because it results in better flow during startup/warmup..
Choosing a heavy weight like 15w50 can definetally have it's advantages in certain cituations, especially in engines that are run for long periods of time under heavy strain. In those situations, the oil gets very hot, and the extra thickness helps maintain proper oil film over parts. Heavy weights are also better for situations where the engine takes on a lot of dirt.
If you are using your trooper under normal circumstances, stick to thinner oils.