Most engine wear occurs at startup. That’s primarily because oils thicken as the temperature drops. Cold oil doesn’t flow as fast and, in some cases, may not be able to flow through tiny oil passages at all. When that happens, engine components are forced to operate without lubrication, accelerating wear. Therefore, cold-flow capability is a critical measure of motor oil performance.
We wanted to know how AMSOIL Signature Series Synthetic Motor Oil stacks up against the competition. So, we hired an independent third-party lab to put Signature Series head-to-head against other motor oil brands. The results are in and Signature Series came out on top.
The graph below shows the difference. Signature Series trumped all other motor oils we tested, providing up to 38% better cold cranking viscosity than Royal Purple. In other words, AMSOIL provides better cold cranking viscosity, helping improve wear protection for engine components at startup.PP
Causes of startup engine wear
The exact percentage of engine wear that occurs at startup depends on a mix of several factors:
- Motor oil doesn’t flow, temporarily starving the engine of oil.
- Gravity causes much of the oil to flow into the oil sump, leaving components unprotected.
- Condensation forms inside the engine that causes rust and corrosion.
- Richer air/fuel mixture at startup washes oil from the cylinder walls.
- Cold piston rings and cylinders don’t seal as well, allowing combustion gases to “blow by” the rings and contaminate the oil.
While all these factors are important, lack of oil due to poor cold-flow properties is the biggest culprit.