Schlemko scored at 8:38 of the second period to put the Sharks up 3-1, two seconds after a goaltender interference penalty on Oilers forward Patrick Maroon ended. Schlemko's wrist shot from the point beat Talbot through traffic.
"It's always disappointing to lose, losing [stinks]," San Jose captain Joe Pavelski said. "There is no way around that. We battled hard tonight and did some good things to take that 3-1 lead, but unfortunately we couldn't battle it out."
Letestu scored on the power play with 1:27 left in the second to get Edmonton within 3-2.
"I thought we played a pretty good game, maybe we sat back a little in the third," Schlemko said. "I thought we did a good job limiting their chances. They had one good shot that they buried. Maybe we weren't on the attack as much as we were in the first two periods."
The Oilers outshot the Sharks 14-2 in overtime, but Jones kept San Jose in the game with several outstanding saves.
"We thought eventually it was going to go in," Letestu said. "He's only human. Eventually the puck's going to find a way to the back of the net. I thought we were pressing the right way. We weren't taking too many chances, they were just kind of coming for us."