The petroleum engineer that has helped me so much with this topic recommends Mobil 1 VTWIN in all three holes. It's available at some Autozones, Advanced Auto, and other bike stores. Wal Mart might even have it. He says, backed up b actual analysis on trannys, engines, and primary samples, that it is highly recommended for all three. He says most of the big rigs you see on the hiways are running Mobil 1, or some other good synthetic like Amsoil, in their transmissions. On straight cut gears, like in a HD, he says there is no advantage to running a gear lube....all it does is rob the engine of horsepower from churning that thick oil, and the protection is no better, and in most cases not as good. I changed to Mobil 1 10 W 40 MT4X (motorcycle oil) in my Ducati and noticed a DRAMATIC improvement in oil temp, shifting ease, and overall performance of the engine...It makes more power, just as he claimed it would.
The Mobil VTWIN oil was developed by one of their Sr. Chemical Engineers (old dude) who had 17 bikes, most of them HD or other vtwins...he had a blank check during development and came up with the best possible syn for the V's. The trannyu is bound to stir up some chit here, but I'm just telling you what I have experienced in a high HP, high torque twin, though it's not a v-twin, but an L (Ducati). Mobil 1 VTWIN is going in my SEUC at the 1K service without hesitation. The thick tranny lubes will protect, but from their research, you get the same protection for the V sys oil, without having to churn butter in the case. You ever tried to stir 70W140? It's like molasses...bound to rob HP, but provides no better film protection, or wear characteristics, as has been proven by their analysis.
That's my opinion