After winning the toss, Adelaide elected to to bowl first against the Sixers, who were playing their first game since import Tom Curran received a four-game ban for umpire intimidation.
Following a fast start on Friday night, the Sixers lost 3-1 after the powerplay ended and only vice-captain Silk (66 not out from 45 balls) was able to make a fist of things from there.
The Sixers fan favourite brought up his seventh BBL half-century in the penultimate over with a four past deep backward point.
On the last delivery, he smacked Wes Agar for the only six of the innings to help the Sixers post a better score than looked likely when they slumped to 5-120 in the 17th over.
As the Sixers push to remain unbeaten this summer, the bowling attack will need to defy the absences of allrounder Curran and star paceman Sean Abbott, who missed through illness.
Towering English paceman Jamie Overton (3-23) dismissed Sixers openers James Vince (10) and Josh Philippe (25) in the space of three balls to put the brakes on the hosts.
They'd finished the fourth over at 0-39, but when 100-gamer Daniel Hughes was caught behind for one, the Sixers were in serious trouble at 3-40.
Wicketkeeper Harry Nielsen's catch dispatched of Hughes after he had sent Philippe on his way with another good grab behind the stumps three balls earlier.
Silk helped reignite the slow-and-steady Sixers with back-to-back fours off Agar's bowling in the 13th over.
But he and Moises Henriques were left to rue their decision not to capitalise on their 66-run partnership by taking the power surge in the 15th over.
Henriques skied one from Overton and was caught, leaving the Sydneysiders to regroup again.
Silk continued to anchor the innings even as Joel Davies (10) and Jack Edwards (12) fell around him.
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