There's a lot of allure to a Harley Davidson motorcycle, for bike enthusiasts and non-bikers. But like any bike or motor vehicle, a Harley is a machine, prone to mechanical problems and breakdowns.
Historical Oil Issues
- Earlier Harley models -- from 1939 to 1941 -- had chronic oil problems. The problems on these bikes, nicknamed Knuckleheads due to the defining overhead valve design, came from a dry sump oil system. Oil was distributed unevenly and oil leaks would occur. It wasn't until 1941, when a new oil unit was installed, that the problem was entirely overcome.
- A well-documented debate raged through the late 1990s and early 2000s, with oil manufacturers going toe-to-toe through editorials in "American Iron Magazine." Harley Davidson engines, according to the manufacturer, were meant to run a specific, Harley brand non-synthetic oil. Rumors were that Harley didn't honor warranties if other oils were used (which wasn't true) and the conclusion of one of the authors of the debate is that using synthetic oil in a Harley won't lead to any serious issues.
- According to "Synthetic Motor Oils," a problem called oil carryover (or slobbering) occurs in Harley Davidson motorcycles. The issue arises if the backplate air filter bolts or tubes become cracked, deteriorate or are improperly attached.