Lower Unit Oil ?

[Bear700]

Does anyone know what the viscosity of the oil used in the lower unit? I just bought some and want to make sure it is right. I have a 1979 55HP Johnson, mech. shift if that matters. Thanks!

 

[R.Johnson]

Re: Lower Unit Oil ?

Older engines us GX-90 hyphoid oil. I don't know about the newer lube's, probably 70-80. If your thinking of a cheaper lube from Tractor Supply, don't do that. These marine lube's have other qualities other lubes don't have. Such as some tolerance to water intrusion.

 

[Vic.S]

Re: Lower Unit Oil ?

Use an outboard gear oil to API GL 5 spec. it'll be in the SAE 80 to 90 range. You may have choce of mineral or synthetic .. choice is yours. (not type C oil)

They tell us that the outboard gear oil contains extra inhibitors to guard against the effects of water ingress