The difference between the pour point and the pour point of gear oil

The difference between the pour point and the pour point of gear oil

Although both are low-temperature performance indicators for gear oils, there are fundamental differences between channeling point and pour point:

I. Definitional Differences

Pour Point
Represents the minimum temperature at which the oil remains flowable during cooling, reflecting overall fluidity under gravity. For example, the pour point requirement for GL-5 80W/90 gear oil is no higher than -35℃.

Channeling Point
Specifically refers to the oil's ability to flow back and cover the container bottom within 10 seconds after channeling (grooving) when stored at a specific low temperature (e.g., -45℃) for 18 hours, emphasizing low-temperature fluidity during gear tooth contact.

II. Testing Method Comparison

The test standard for ‌pour point‌ is ‌GB/T 3535‌, with the key step being cooling to the highest temperature at which the liquid surface ceases to move.
The test standard for ‌channeling point‌ is ‌SH/T 0030‌, with the key step observing whether the oil flows back within 10 seconds after channeling.

III. Application Scenarios

Pour Point
Guides operational measures for low-temperature transportation/storage, such as selecting gear oil with pour point 10℃ below ambient temperature in northern winters.

Channeling Point
Directly correlates with lubrication capability during cold starts, e.g., 75W gear oil requires ≤-45℃ channeling point to ensure initial lubrication for hypoid gears in extreme cold.

IV. Data Relationship

For the same oil, channeling point is typically lower than pour point, e.g.:

Pour Point: -40℃

Channeling Point: -48℃

The ‌SH0030 Gear Oil Channeling Point Tester‌ is designed and manufactured in accordance with the standards ‌SH/T 0030-1990‌ "Determination Method for Channeling Point of Vehicle Gear Oil" and ‌FTMS791B3456.1‌, and is suitable for determining the channeling point of gear oil using the methods specified in the above standards.‌