Heavy rains delayed play for nearly four hours early in the round. Those who were unable to complete their rounds on Thursday will return to Loch Lomond at 2:30 AM ET Friday.
'I didn't leave anything on the golf course today. I got just about everything out of my game today and it was nice to do that again,' said Els, who won this event in 2000. 'It brings back good memories from the start of the year.'
Els, who was on fire earlier in the year with a pair of victories on both the PGA and European tours, started on the back side and parred his first three holes before a birdie at the 13th.
Colin Montgomerie matched par with a 71, while Phil Mickelson and former U.S. Open champion Retief Goosen both shot 76.
The South African, who will defend his British Open title in one week at Royal St. George's, reached the green off the tee at the short par-4 14th and two-putted for another birdie. Els then ran home a long birdie putt at the par-4 15th to make it three in a row.
Els kept plugging along and hit his approach inside 18 feet for a birdie at the par-4 18th. He made the turn at minus-4 and continued his fine play on the inward half with a birdie at the first after his second shot landed five feet from the cup.
A bad drive at the 13th left Els to play his second shot underneath a tree in a crouched position. He managed to save par and then tallied a birdie at the par-5 sixth to reach 6-under.
At the par-4 seventh, Els dropped his approach within 10 feet for yet another birdie en route to a bogey-free round.
'I've only played one round,' said Els. 'It's not like I'm totally back, but I haven't totally lost it either. I just felt that my putter let me down a little bit here and there and mentally I wasn't as fresh and I had a nice break now so everything's coming back.'
Howell also played the back nine first and picked up his first birdie at the par-4 12th. He double bogeyed the par-5 13th but was able to recover with back-to-back birdies starting at the 15th.
The Englishman, who had missed significant time with multiple injuries, played a spectacular inward nine with four birdies for a round of 5-under 66.
'I was out for 11 weeks with the broken arm and seven weeks with the shoulder injury,' said Howell. 'But maybe that is an omen in that I sprained my ankle playing tennis in 1998 and missed eight weeks before coming back and winning the Dubai Desert Classic.'
Phillip Price, who won last week's European Open, finished at 4-under-par 67 in the clubhouse along with Peter O'Malley, Martin Maritz and Terry Price.
'I struggled with my concentration a bit out there but putted well,' said the Welshman Price. 'I didn't have a clue and had problems with my concentration initially, but I felt if I paid a little more attention I would be fine.'
Reigning U.S. Amateur champion Ricky Barnes had a solid day with four birdies and three bogeys for a 70.
Defending champion Eduardo Romero completed a round of 1-over-par 72 on Thursday.