Classic 50 lower unit lube

[Mustang67ford]

My local boat shop in the past has sold my quicksilver high performance sae 90 gear lube for the lower unit which I had been using. I was on the phone talking to mercury on another item but then asked them about the gear lube. They said I should be using mercury 80w90 premium gear lube and the sae 90 is for 75hp and above. Questioned the boat shop and they are staying behind the sae 90 recommendation.

Reading further into it, I read where it said not to mix these two. So, do I stay with the 90 or switch to the 80w90 and if switching, how do I get all the 90 out?

On a side note, is the drain and vent plug washer recommendation still the yellow ones #830749?

 

[fitz73222]

Hi Mustang '67,
use the Mercury high performance gearoil, available everywhere. She'll be glad you did.

 

[timguy]

Right and don't worry about mixing to that little bit that will stick inside. Drain when warm....heat with hair dryer even.

 

[Mustang67ford]

Hi Mustang '67,
use the Mercury high performance gearoil, available everywhere. She'll be glad you did.

Thanks, will stay with the high performance sae 90.