Ask Any Jeeper: These Are the Engines You Can Count On

10. 4.0L Inline-Six

The legend. If you ask Jeepers what engine they trust most, you’ll hear "the 4.0" more than once. It ran from 1987 to 2006 and was known to hit 300K+ miles with just basic maintenance.

It’s not fancy—cast iron everything, old-school pushrods—but that’s exactly why it’s so dependable. Great torque, simple design, and a DIY dream. If reliability had an engine mascot, this would be it.