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Engine & Gear Oil - Recommended Viscosity vs. Outside Temperature

Oil viscosity vs. temperature.

All lubricants have practical limits when it comes to operating temperatures.

  • Lower temperatures and increased viscosity may restrict lubrication - causing metal to metal contact and damage to the machines
  • Higher temperatures and reduced viscosity may limit lubrication film thickness - causing metal to metal contact and damage to the machines

engine oil

For most machines - like car engines -  the critical point of operation is at startup before reaching operating temperatures. In cold weather lubricants with adequate viscosities at start up temperature are required.

Engine Oil

The table below indicates appropriate engine oil viscosity vs. outside (start up) temperatures. 

Engine & Gear Oil - Recommended Viscosity vs. Ambient Temperature
Engine Oil
SAE Viscosity
Temperature
-20 oF
(-29 oC)
0 oF
(-17.8 oC)
20 oF
(-6.7 oC)
40 oF
(4.4 oC)
60 oF
(15.6 oC)
80 oF
(26.7 oC)
100 oF
(37.8 oC)
20W-20              
20W-40              
20W-50              
10W-30              
10W-40              
10W              
5W-30              
5W-20              

Note that machine operating temperatures - and lubricant temperatures - does not change significantly with different ambient temperatures. In most cases operating temperatures of engines are above the temperatures in the table above.

Gear Oil

The table below indicates recommended gear oil viscosity vs. outside (start up) temperatures. 

Engine & Gear Oil - Recommended Viscosity vs. Ambient Temperature
Engine Oil
SAE Viscosity
Temperature
-20 oF
(-29 oC)
0 oF
(-17.8 oC)
20 oF
(-6.7 oC)
40 oF
(4.4 oC)
60 oF
(15.6 oC)
80 oF
(26.7 oC)
100 oF
(37.8 oC)
75W              
80W              
80W-90              
85W              
90              
140              

Note that the tables above indicates average data. For specific information - check manufacturing data. 

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