Jean Hugo had the low round of the day with a 64 to join Warrick Druian and Craig Lile in a tie for second place at 11-under-par 133.
Van Staden played the back nine first and jumped out of the gate with back-to- back birdies from the 10th.
The 39-year-old added a birdie at the 15th and reached 10-under with a pair of birdies starting at the par-5 17th
'I've been struggling with my rhythm,' said van Staden. 'But once you find it again it doesn't feel so hard.'
Van Staden made it three in a row with a birdie at the first and capped off his bogey-free round with a birdie at the fourth to find himself in an unlikely position.
'I can't remember when last I led a tournament,' said van Staden, who is seeking his second career victory on the Sunshine Tour. 'I'm a part-time golfer, but maybe I should start taking it a bit more seriously now because there are so many good young golfers out there.'
Hugo also enjoyed a round without a bogey, collecting eight birdies on his way to a share of second.
'It's difficult to say if I'm getting back to my old form,' said Hugo. 'You just don't know how many 64s there are going to be. I'm keeping my goals modest at the moment.'
Defending champion Michiel Bothma and Desvonde Botes carded matching rounds of 66 to finish at 10-under-par 134. Thomas Aiken and Mark Murless were one shot further back at 9-under-par 135.
Opening-round co-leaders Roger Wessels and Thabang Simon, who each fired rounds of 63 on Thursday, both struggled in the second round.
Wessels managed a 76 to finish seven shots off the lead at 5-under-par 139 while Simon struggled to a 77 to finish in a group at 4-under-par 140.
The 36-hole cut fell at 2-under-par 142 with 70 players qualifying for the weekend.