Free tools and guides from Don's Garage.
Honest answers, working calculators, and field-tested checklists from a third-generation Denver shop that's been doing this since 1970. Choose your path below.
Running a fleet? Take a look at our fleet maintenance program alongside the tools below.
The resources here are split into two sections, and fleet operators come first. The fleet section covers a downtime cost calculator, maintenance schedules, a DOT inspection checklist, and a fleet transmission guide.
The car owner section covers a repair-or-replace calculator, a transmission quiz, a used-car inspection checklist, and a transmission guide. Every tool and guide on this page is free to use.
Don's Garage has been family-owned since 1970, and these pages are written the way the shop talks across the counter: plain and to the point. If a term trips you up, there is a glossary of fleet and transmission terms in plain English.
For Fleet Operators
Downtime cost calculator, severe-duty PM schedules, DOT inspection readiness checklist, and our fleet transmission & drivetrain guide.
See fleet resources →
For Car Owners
Repair-or-replace calculator, transmission guide, used car pre-purchase inspection checklist, and our 90-second transmission diagnosis quiz.
See car-owner resources →Need a real diagnosis? Bring it in.
Free tools are great. A real second opinion from a third-generation Denver mechanic is better.