I had the slant 6 in the 199 cu in version. Ran it to 187,000 miles without ever needing to have a valve cover off. I don't remember the oil filter being an issue at all. The slant 6 like the 4.0 I6 Jeep would run to 250,000 miles with minimal care. Too bad they have been replaced with Aluminum block/head efficient engines that turn to scrap with one overheat problem.