Trans fluid vs gear oil

[ws23rt]

I have adapted a right angle gear drive to fit where the tail shaft housing mounts on a 727 trans. I have back to back seals at that connection but if they leak or fail the fluids could mix. Maybe no big deal but my sense (or lack of it) tells me I need gear oil for the spiral miter gears. It would be ideal to have one type of fluid so that seal issue would be moot. No torque converter, no governor. Manual shift by front pump flow control. Any opinions or input welcome.

[John_Kunkel]

I would think those gears require an extreme pressure (EP) lubricant. You could probably find an EP luricant that would be thin enough to work in the 727 but you might run into seal material compatability problems.

Turbine engine oil has EP additives and it's pretty thin. 

[ws23rt]

Thanks for the reminder that viscosity is more important in the trans. I suspect that ep additives would cause little or no trouble in my application but I do have concern about the miter gears.