Checking Lower Unit Lube '77 35 horse Rude

[KC8OIT]

I've ordered a manual for my Motor, but I would like to check the fluid in my lower unit before this weekend. From where do I check it and what grade of lube do I use? Thanks in advance.

 

[tgissel]

Re: Checking Lower Unit Lube '77 35 horse Rude

KC80IT, There should be a screw normally a flat-head @ the bottom of the lower unit that drains the fluid, and another screw also a flat-head that will relieve the pressure so that the fluid can actually drain because it is so thick. The fluid type should be a good quality SAE 80W-90 API w/ a GL5 rating. Just open the bottom screw a little and let some drip out on your finger to get an idea of the condition of the fluid, it should be dark brown. Good Luck,

 

[KC8OIT]

Re: Checking Lower Unit Lube '77 35 horse Rude

Thanks Thad, as an auto tech, I have plenty at work, I'll grab a couple extra quarts I have on my bench. Any Idea of capacity? Or is it similar to a Rear differential, fill to the vent?

 

[bubbakat]

Re: Checking Lower Unit Lube '77 35 horse Rude

You can't use the automotive kind it has to be marine grade oil.

 

[tgissel]

Re: Checking Lower Unit Lube '77 35 horse Rude

Bubbakat is correct in stating that you can not use automotive type, you should use marine grade w/ GL5 rating. But yes you do fill to the vent hole, and then let just a little drip back out the lower hole to allow for expansion. Good Luck!

 

[Scaaty]

Re: Checking Lower Unit Lube '77 35 horse Rude

NEVER use automotive 80/90 or whatever other API #. It can foam, cavitate, blow your seals, etc. in a lower gearcase. Automotive app's have vents. ALWAYS use the correct type of marine lower unit gearlube. Usually 80/90 REG or SYN will work in 99% of any lower unit. And change it yearly before putting up for the winter. ANY water in there left to freeze will have you buying a new case.

 

[KC8OIT]

Re: Checking Lower Unit Lube '77 35 horse Rude

O.K. I get the hint, I'll use Marine Grade Lube. Thanks to all who replied. I was actually wondering if there was a marine Grade and you guys answered my question. I'm still wet behind the ears, it's my first boat. My father had a nice one, I grew up on Lake Erie, Walleye fishing but he always did the maintenance and I never paid attention to how it was done. Once again, Thanx to all!<br />Mike