Volvo DPS outdrive trans: OCI?

[lars11]

The Volvo Penta outdrive manual states that you should change the fluid every 50hrs or yearly. Now, it is a bit of work involved and the fluid (only Volvo OEM 75w90 Full Synthetic or Mobil 1 75w90 Full Synthetic) is quite expensive.

Any input on longer intervals? I checked the drive for water in the fall but it seemed clean. Can the fluid really be shot at only 50 hrs?

 

[unDummy]

Outdrives tend to be run under load. Think of it as driving with the pedal to the floor, or plowing, or towing.
50hrs could be barely acceptable. Simple UOA your fluid after 50hrs and see if you could go longer.
I'd wager that the sump is too small to go any longer when you consider the average power/load it sees, along with the fear of moisture buildup.

Unless you use the boat 50hrs a week, I don't see the $10-quart M1 as too expensive. BTW, any of the GL5 90wt full synthetics should work well.