The Mariners have downed the Athletics in each of their last six meetings.
Silva (3-0) allowed only four hits and a run over seven innings and his job was made easier by Seattle's five-run outburst.
Greg Norton drew a walk to load the bases again and another walk, to Kenji Johjima, forced in a run. A fielder's choice grounder from Willie Bloomquist accounted for the fourth run of the inning and Yuniesky Betancourt singled in another.
After winning six games out of seven, Oakland has dropped three in a row.