HD Synthetic 75w-90, how hot can it get?

[sdan27]

We have a two speed gear box on a piece of farm equipment that runs the drive wheels. It holds about 5 gallons of oil that the manual says to use 80w-90 gear oil. The other day it got kinda hot and was puking oil out of the breather. The next morning I drained it and refilled with a 75w-90 synthetic. After operating the machine all day the next day I checked the temperature on the outside of the gear box and it was about 270 deg F. How much temperature will synthetic oil like that usually hold up to?

 

[Joe_Power]

400-500

 

[oilboy123]

I would not worry about the syn gear oil at all. Just check its condition every once in awhile.

 

[MolaKule]

You have about another 135F to go before it reaches the Flashpoint.

It will oxidize faster at higher temps so check at the end of each day's operation.

Was this read with an IR meter?

 

[sdan27]

Yes, I used an infrared gun I have. How much heat will standard 80w-90 stand up to?

 

[ironman_gq]

A hard working differential in a truck can hit 250-300 pretty regularly when running near the rated load of the vehicle. With synthetic fluid I wouldn't worry too much about it. At most I would check the oil level and look for signs of burning before you start every day, it lived this long on regular dino I would expect it to be even better on synthetic.