A grease’s dropping point is the temperature at which it becomes fluid enough to drip in a standard laboratory test; it is not the temperature the grease can work at. The ASTM test method itself states that above 200 °C the dropping point has no correlation with a grease’s maximum operating temperature. Published operating ranges from major grease makers sit 50 to 120 °C below their dropping points.
This page explains how dropping point is measured, how far below it real greases are rated to run, and how to pick a grease for a hot bearing. It is published by Zhongtian, a grease manufacturer, and uses data printed on manufacturers’ own data sheets.
How is grease dropping point measured?
A small sample is heated in a cup under set conditions, and the dropping point is the temperature at which the first drop falls from the cup’s opening. The current method is ASTM D2265, the “wide temperature range” test using an aluminium block heater. The older ASTM D566 method was withdrawn in 2023 and was not recommended for bath temperatures above 288 °C. Other methods seen on data sheets include ISO 2176 (used by SKF), IP 396 (used by Shell and Chevron) and, in China, GB/T 3498 and GB/T 4929.
ASTM describes dropping point as useful for identifying the type of grease and for quality control. It is a static test: the grease is not sheared, pumped or exposed to air over time, which is what shortens its life in a bearing.
Dropping point vs operating temperature: real data sheet figures
The gap between the two numbers is large on every reputable data sheet. These are figures printed by the manufacturers themselves.
| Grease (thickener) | Dropping point | Published operating range | Gap to upper limit |
|---|---|---|---|
| Mobilux EP 2 (lithium) | 190 °C (D2265) | −20 to 130 °C | 60 °C |
| Mobilith SHC 220 (lithium complex, synthetic) | 265 °C (D2265) | −40 to 150 °C | 115 °C |
| Shell Gadus S2 V220 2 (lithium) | 180 °C (IP 396) | −20 to 130 °C | 50 °C |
| Shell Gadus S3 V220C 2 (lithium complex) | 260 °C (IP 396) | −20 to 140 °C (peak 150 °C) | 120 °C |
| SKF LGMT 2 (lithium) | >180 °C (ISO 2176) | −30 to 120 °C | 60 °C or more |
| SKF LGHP 2 (di-urea) | >240 °C (ISO 2176) | −40 to 150 °C | 90 °C or more |
| SKF LGWA 2 (lithium complex) | >250 °C (ISO 2176) | −30 to 140 °C | 110 °C or more |
| Chevron Delo Grease EP 2 (lithium complex) | 262 °C (IP 396) | −30 to 140 °C | 122 °C |
The pattern holds across makers: a simple lithium grease with a dropping point around 180 to 190 °C is rated to about 120 to 130 °C, and lithium complex greases with dropping points of 260 °C or more are rated to about 140 to 150 °C for normal service.
Why does grease fail long before its dropping point?
At high temperature the base oil oxidises, evaporates and bleeds out of the thickener long before the structure melts. The grease hardens, loses oil and leaves deposits, so the bearing runs short of lubricant while the grease still looks solid. In our sales training we teach a simple rule of thumb: in use, grease life roughly halves for every 10 to 15 °C rise in temperature. That is why relubrication intervals at the top of an operating range are much shorter than at the middle.
- Base oil decides oxidation and evaporation. Synthetic base oils generally extend the usable range.
- Thickener decides the dropping point and how the grease holds oil. Clay (bentonite) thickeners do not melt at all, so their dropping point says little about high-temperature life.
- Speed, load and contamination add frictional heat and shorten life further.
What is the difference between dropping point and melting point?
Grease does not have a sharp melting point. It is a thickener holding oil, and it softens progressively as it heats. The dropping point is the standard way to put a number on the temperature at which it starts to flow under test conditions. Some thickeners, such as bentonite clay, never melt, and their tests report either a very high dropping point or none at all.
Zhongtian greases: dropping point and service temperature
For comparison, these are the dropping points and service temperatures printed in our own catalogue and product pages.
| Zhongtian grease | NLGI | Dropping point | Service temperature |
|---|---|---|---|
| Automotive general-purpose lithium grease | 2 / 3 | ≥180 °C | −20 to 120 °C |
| Molybdenum disulfide lithium grease | 0 to 3 | 170 to 175 °C (GB/T 4929) | −20 to 120 °C |
| Heavy-duty truck wheel hub bearing grease | 2 / 3 | ≥280 °C | −30 to 200 °C |
| HEP high-temperature grease | 3 | ≥310 °C | −30 to 220 °C |
| Polyurea grease | 2 | ≥260 °C (GB/T 3498) | −20 to 220 °C |
| Bentonite grease | 1 to 3 | 270 °C (GB/T 4929) | −30 to 250 °C; our technical team advises that long-term use above 204 °C shortens service life |
Treat the top of any service range as a short-term or carefully monitored limit, not a continuous design point, and shorten relubrication intervals as temperatures rise.
How do I choose a grease for a hot bearing?
- Start from the measured bearing temperature, not the ambient temperature, and add a margin for peaks.
- Compare operating ranges, not dropping points. Use dropping point only to compare greases of the same type tested by the same method.
- Check base oil and relubrication access. If the bearing cannot be regreased often, choose a grease with more margin, often with a synthetic base oil.
- Check compatibility before switching thickeners, and purge the old grease where possible.
Our free grease selector filters greases by operating temperature, and our high temperature grease guide compares grades above 150 °C. For clay-thickened greases, see bentonite grease limits. Send us the bearing temperature, speed and relubrication interval and we will suggest a grade.
Frequently asked questions
What is a good dropping point for grease?
It depends on the thickener. Simple lithium greases are typically around 180 to 200 °C, lithium complex and polyurea greases 240 to 290 °C. A higher dropping point is not, by itself, a higher operating temperature.
What is the rule of thumb between dropping point and operating temperature?
There is no fixed offset. On the data sheets above, the published upper operating limit sits 50 to 122 °C below the dropping point. Use the maker’s operating range.
Is ASTM D566 still used?
ASTM D566 was withdrawn in 2023. ASTM D2265 is the current method and covers higher temperatures.
Sources
- ASTM D2265-22, Dropping Point of Lubricating Grease Over Wide Temperature Range
- Mobil, Mobilux EP 2
- Mobil, Mobilith SHC 220
- Shell, Gadus S2 V220 2 data sheet
- Shell, Gadus S3 V220C 2 data sheet (en-AU)
- SKF, LGMT 2 data sheet
- SKF, LGHP 2 data sheet
- SKF, LGWA 2 data sheet
- Chevron, Delo Grease EP 2 data sheet (EU, 2024)
- Zhongtian product catalogue and product data sheets