Lower Unit Gear Lube

[NDcarper]

I(n an samll 6hp outbard is there any advantage in using synthetic motor oil in the lower unit gear case?
In my automobile my manual transmission fluid is never changed per manual. Only reason to change the unit oil in outboard is becasue it accumulates water.

 

[Dick in Falls Church]

Have had folks tell me that they picked up more rpm after change to synthetic in lower unit.

 

[NDcarper]

sorry motor oil is a typo. Should be gear oil.

 

[another Todd]

ND---why would you use synthetic motor oil in the lower unit? A synthetic lower unit oil would be better.

 

[Donald]

Some of the lower units in high HP applications get very hot and synthetic gear lube should help. But Merc high performance gear lube (snot green) is also very good gear lube.