We are one of Stillwater’s oldest and largest independent service centers. We have a 7200 square foot facility, 5 ASE certified technicians and state of the art equipment. We are a member of the Better Business Bureau, Stillwater Chamber of Commerce and are active in two automotive associations, the Automotive Service Association and the Alliance of Automotive Service Providers. We are a complete bumper to bumper mechanical service and repair facility for domestic and import vehicles including light trucks. We stand by all our repairs with a one year/12,000 mile warranty.

 Stillwater Automotive Diagnostic Center was founded by Happy Thomsen Sr. in 1989. Happy has spent most of his life working as a mechanic. He owned a service station in Stillwater, kiddy corner from the Lowell Inn, worked for Bud Snow Texaco on Arcade and Maryland in St. Paul and worked for Countryside Repair in Stillwater. He started Stillwater Automotive Diagnostic Center in August of 1989 and was financed by Lake Elmo Bank. Happy wanted to continue his passion of helping people, by fixing their cars and light trucks. With the loyal customer base expanding, Happy hired some of the best and the brightest automotive superstars!! His goal was always to provide honest service and repairs while earning your trust. Today, Stillwater Automotive Diagnostic Center has 5 ASE Certified technicians and helpful, friendly service advisors.