Oosthuizen ended on a 280 total, eight under for the week after rounds of 69, 71, 71 and 69.
The world no 7 was three shy of a playoff which Australian Brett Rumford won. With 120 putts for the event, Oosthuizen accounted for 43 percent of his shots on the greens.
Rumford, incidentally, had just 105 putts for the week yet was only three shots ahead of Oosthuizen.
"Yeah, I've been playing, hitting the ball probably the best I've been in a while, hitting it," Oosthuizen said after the round.
"And just missing loads of putts. But still, a lot of positives." The 2010 Open Champion broke 30 putts just once in the four rounds on the first day's play on Thursday where he had 27 strokes.
Positives there were, as he averaged 261m off the tee for the week and 279m in the final round.
Oosthuizen's long driving also included a 450m drive in round two on the par five 10th, though his tee shot was aided by a cartpath where the ball continued to roll towards the hole for minutes after it had been struck.
"I haven’t properly hit the ball this good in a while," said Ooshtuizen. "But after my first nine holes, I was a bit clueless on the greens. I couldn’t really make anything. "I hit two awful tee shots on 13 on Sunday and Saturday and that cost me five over for the two days, which is not very good. But, all in all, I’m very happy.
"I just wanted to get a good number in the final round, to at least put my name up on the leaderboard.
"All in all, though, I’m very positive about this week."
Jbe' Kruger, meanwhile, struggled over the weekend to settle for a score of one under for the week.
Kruger was perfectly placed after the second round at six under after rounds of 71 and 67, but a third round seven-over 79 killed his title aspirations.
"You never know what might happen over the weekend," said Kruger before he battled to improve his worst score of the week. Kruger completed his tournament with a last round 70.
Kruger ended one under for the event and settled for a share of 40th.
Kruger also had his struggles on the greens, especially in his third round where he used the short stick 34 times on the putting surfaces.
The 26-year-old, however, blew hot and cold as he only needed 23 putts on Friday, which helped him to his best round of the week.
Leading final scores at the Ballantine's Championship in Icheon, South Korea, after the fourth round on Sunday (par 72):
(* denotes playoff winner)
277 - *Brett Rumford (AUS) 73-67-69-68, Marcus Fraser (AUS) 70-70-69-68, Peter Whiteford (SCO) 70-69-69-69
279 - Romain Wattel (FRA) 70-69-71-69
280 - Louis Oosthuizen (RSA) 69-71-71-69
281 - Kim Hyung-Sung (KOR) 71-69-74-67, Thongchai Jaidee (THA) 71-72-73-65, Stephen Gallacher (SCO), 70-68-75-68, Alexander Noren (SWE) 71-67-69-74, Pablo Larrazabal (ESP) 70-70-68-73
282 - Hong Soon-Sang (KOR) 71-71-73-67, Kim Gi-Whan (KOR) 65-72-75-68, S.S.P. Chowrasia (IND) 71-70-73-68, KT Kim (KOR) 74-68-71-69, Kiradech Aphibarnrat (THA) 71-66-75-70, Jose Manuel Lara (ESP) 71-67-72-72
283 - Jason Knutzon (USA) 72-70-73-68, Joo Heung-Chol (KOR) 70-70-74-69, Kieran Pratt (AUS) 67-77-69-70, Jyoti Randhawa (IND) 72-69-72-70, Park Sang-Hyun (KOR) 74-69-69-71, Wade Ormsby (AUS) 70-67-74-72
284 - Hwang Jung-Gon (KOR) 70-74-71-69, Wu Ashun (CHN) 75-65-73-71, Gregory Havret (FRA) 71-70-72-71
285 - Mohd Siddikur (BAN) 74-69-71-71, Johan Edfors (SWE) 67-75-74-69, Rikard Karlberg (SWE) 63-73-74-69, Arnond Vongvanij (THA) 68-69-76-72, Berry Henson (USA) 70-70-77-68