The pilot of a small high winged vintage aircraft; unfamiliar with the airport and high density altitude operations; lost control during the landing flare in a modest crosswind and a ground loop and runway excursion resulted. No damage or injuries resulted.

Narrative

I stopped at Columbus; Montana to consult with a Mechanic on normal oil temperatures and pressures for the engine at this density altitude and heat; as I am very unfamiliar. While there; another plane landed with engine trouble and I decided to go to Billings; as I was headed that way and the other pilot needed a ride back there.For the landing at Billings; the wind was given as 190 @ 6 KTS and I was assigned Runway 28R by the Tower. I was completely unfamiliar with the airport as this was my first time coming through on a long cross-country and had only looked up the information right before coming half an hour earlier. I got busy trying to find the airport; find the landing traffic; and talk to Tower. While I considered the wind; I figured it was a direct crosswind; and 6 KTS did not seem difficult.On the landing flare; I realized I was going faster than I expected (I was [not] used to the density altitude in Montana; so I assumed it must be that) and as I touched down I realized I did not have enough crosswind correction in. The airplane went right and I added power to go around - too late; too slow; too much power. I skidded off the runway and swung around onto grass. I was going slowly enough and the grass was slippery enough that the wheels stayed on the ground and neither wingtips nor prop were endangered. However; the plane was out of my control.I contacted the Tower; reported we were okay and got out to check the aircraft. There was no apparent damage. I then taxied back onto the runway and to the ramp; feeling like a complete failure as a pilot.I suspect there may have been a quartering tailwind component instead of the reported direct crosswind. However; my inexperience with density altitude; unfamiliarity with the airport; failure to request a different runway; and failure to correct promptly and correctly for the crosswind and initial swerve that started the ground loop are far more at fault than any wind.