What will happen if too high viscosity oil is used in an engine?

Using oil with too high a viscosity can lead to a number of issues in an engine, notably high oil pressure. High viscosity oil is thicker and flows less easily compared to oil with lower viscosity. This characteristic can make it difficult for the oil to circulate effectively, especially during cold starts when the oil is more viscous.

When the oil fails to flow freely through the engine components, it can lead to blockages or restricted flow, which in turn causes pressure to build up. This excessive pressure can potentially harm engine seals, gaskets, and other components that are not designed to handle it.

In this context, while higher viscosity oil may seem beneficial for lubrication at high temperatures or under high load, its negative impact arises in a scenario where it restricts normal oil circulation and ultimately leads to high oil pressures that can jeopardize engine integrity.

Lower viscosity oils, on the other hand, are designed for better flow and provide adequate lubrication at various temperatures, thus reducing the risk of excessive pressure build-up and promoting better engine performance.