Rod Spittle, who played in three events during the 2006 Champions Tour campaign, posted a 5-under-par 67 and is alone in second place at the TPC at Eagle Trace.
Graham Banister, a former amateur from North Carolina, and Jerry Impellittiere, a club pro from New York, are knotted in fourth place at minus-4.
Ruangkit opened on the back nine Wednesday and he parred his first two holes before back-to-back birdies at 12 and 13. He parred the next four on the back nine and closed with a birdie at the par-4 18th.
He flew out of the gate on the second nine in round one as he birdied four of his first five holes. Ruangkit handled the windy conditions and parred out for the first-round lead.
'Today, I managed to have the right distance on every club and my putting was very good,' Ruangkit said through an interpreter. 'There was no wind during my practice round, but it was very windy when I got to the first tee this morning. I just happened to pick the right club on each shot into the greens.'
Ruangkit is a five-time former winner on the Asian Tour and in 1995 finished second on that tour's Order of Merit. His last win on that circuit came at the 2004 Thailand Open.
This year marked the second time Ruangkit went through the Q-school process. Last year, Ruangkit was an alternate at the regional stage in California, but did not get into the finals. This year at the regionals, Ruangkit tied for eighth and moved into the finals.
Doug LaCrosse and Frank Shikle, both of whom played some events on the Champions Tour in 2006, are tied for fifth place at 3-under-par 69.
Jon Fiedler, Greg Hickman, Mitchell Adams and Robert Thompson share seventh place at 2-under-par 70.
The top-30 players and ties will become eligible to compete in qualifiers held for open, full-field Champions Tour events next season. The field will be cut after 36 holes to the top 70 players and ties, plus any players within 10 shots of the 30th position.