TCW-3 for outboard oil, but what about Lower Unit Gear Oil

[NelsonQ]

Ok, I don't want to start a discussion on 2 stroke oil as there is enough information on these forums to cover it.

I did a search with no luck on the lower unit gear oil.

When at Walmart last night, I was ready to purchase oil for my lower unit, however I noticed that they had all different types/flavours (no, I didn't taste them)

Some were 80W-90, some were simply listed as SAE-90, some 75W-90 synthetic.

Then there are three API service categories for gear oils.

API-GL1, API-GL4, API-GL5.

Most outboard manufactures recommend API-GL5 gear oil for their lower units (from what I read, but I really don't know). API-GL5 gear lubricants are for both mechanical shift units calling for type B gear oil and electrical shift mechanisms calling for type C gear oil (only the viscosity value will be different for each application)

I'm awaiting my service manual to arrive in the mail, so I don't know what my Johnson requires.

So, after all this, what do I buy? I would like to use full synthetic, but at this point, I'm just confused.

I don't want to use too thin an oil or start a debate on brands, I just want to know what's recommended.

Now, let the games begin

 

[tashasdaddy]

Re: TCW-3 for outboard oil, but what about Lower Unit Gear Oil

lower unit, super tech 80-90 lower unit oil, will be fine in you 115hp. no need to go synthetic there. i use all super tech products, boat and cars, mowers.

 

[5150abf]

Re: TCW-3 for outboard oil, but what about Lower Unit Gear Oil

You don't want "gear oil" you need lower unit oil, they are different.

Lower unit oil has additives to help deal with water intrusion gear oil doesn't.

As TD said Walmart lower and 2 stroke oil are fine just be sure it is marine lower unit oil.

 

[NelsonQ]

Re: TCW-3 for outboard oil, but what about Lower Unit Gear Oil

Thanks guys.

In the past I've simply used Shell brand or Formula 1 (Canadian Tire brand)

I guess being more specific, I believe gear oil meets API-GL4 standards, lower unit oil meets API-GL5 standards and gear oil is insufficient for that use.

But, what really is the true standard (such as TCW-3 for 2 stroke oil)?