Today on my 2012 heritage after riding hard through the twisty's my oil light came on. I shut it down and when I checked the oil which was full it was aerated bad. (foamy) let it sit about 1min and re start no aeration and oil light off. have not had a problem for the rest of my ride 130 miles. The only thing I can think of is that either the oil getting thrown back and forth in the tank caused the problem or can the oil get lower then the pick up line in the tank and suck air. I never have had a problem with my Electra Glide or Super Glide but those have the oil in pan in the bottom. Any one have this problem and is it a common problem with H.D.'s with the oil tank mounted on the frame?

 

The foam in oil is typically due to aeration of the oil and not moisture or condensation in the oil. The foam is not from "sloshing around" in the oil tank.

All Harleys use a dry sump oil system for their engines. The oil will collect in a shallow sump at the base of the engine. A scavenge pump(s) moves the oil from this sump back to the oil reservoir.

Foaming is not unusual for a dry sump system. It can occur when the scavenge pump picks up some air when the sump is very low or "dry".

I don't know what oil you use but some may tend to foam more than others. The foaming is nothing to be concerned about. As you found out, letting the oil sit for several minutes de-aerates the oil and dissipates the foam.

Ride safe, brother.