Playing at home, Park gained a clear win, as Phil Bungard, Kyle and Sean Geary and Antony McCullough all won in style.
Michael Ormandy was the only Oamaru golfer to post a win, beating Park junior Conor Jamison on the 17th green.
With five holes to play, the Park team looked set to win five of the six games but the battle between the No1 golfers finished in exciting fashion.
Mark Collie was four up on Oamaru junior Cameron Ryder with six holes to play but Ryder birdied 14, 15 and 16 to climb back into contention.
Collie was one ahead playing the final hole but Ryder responded, sinking his fourth birdie putt on the final green to snatch the half.
Meanwhile, Otago Blue lies in second place behind Chisholm Park. Balmacewen's top team also has six points and is only half a game behind the leaders with a game in hand.
Otago Blue, also playing at home, beat defender St Clair, winning four of the six games to give St Clair its second loss in three rounds.
Brandon Hodgson led the way at No1, beating Paul Brouwer with two holes to spare, while at No2, Jamie Anstiss was no match for Brent McEwan, who had the game in the bag after turning five up.
St Clair's other win came from Tony Giles at No6, who beat Luke Murdoch.
In the middle order, Michael Smith carded six birdies for 67 to beat Stephen Hitchcox, while Tyrone Ratahi accounted for Clayton More by 4 and 3.
Otago led by 3.5 to 2.5 after six holes but No5 Cameron Grant went from square to three up, giving Otago a 4-2 lead at the 12th.
Chris Snow (No5) was three down with three to play but fought back in dogged style to win the next two holes with a birdie and a par.
Grant sealed the win by sinking a 4m putt for a birdie three on the final hole to finish two-up.
