Is using 5th gear at 40mph messes up my engine?

[john21031]

In my opinion, the risks of causing harm to the engine while driving in a high gear at low speed is significant. Imagine riding a multi speed bike in the lowest gear uphil. This is the time when sproket and chains fail the most, due to highest load, on small number of teeth.

The power needed to turn the smaller diameter of a high gear is much greater than needed to turn (rotate) the lower gear. This stresses the engine, specifically it creates high forces on the crank shaft bearings, wearing them out prematurely.

Another problem of loading the engine at low rpm is a possibility of inadequate oil delivery due to lower oil pressure at low rpm.

Driving these new cars and not seeing major engine problems is not an indication that the engine is not wearing out prematurely.

[nerp]

Originally Posted by john21031

In my opinion, the risks of causing harm to the engine while driving in a high gear at low speed is significant. Imagine riding a multi speed bike in the lowest gear uphil. This is the time when sproket and chains fail the most, due to highest load, on small number of teeth.

The power needed to turn the smaller diameter of a high gear is much greater than needed to turn (rotate) the lower gear. This stresses the engine, specifically it creates high forces on the crank shaft bearings, wearing them out prematurely.

Another problem of loading the engine at low rpm is a possibility of inadequate oil delivery due to lower oil pressure at low rpm.

Driving these new cars and not seeing major engine problems is not an indication that the engine is not wearing out prematurely.

Understood. That's why we're all saying that 40-45mph in fifth is perfectly fine on flat pavement. We like to downshift when going uphill or needing to accellerate.