gear oil specs--how important?

I had the boat out of the water for spring cleaning and maintenance; the LU oil was black (Saturday) so Sunday had a pang of conscience and instructions from iboats so I changed it. The recommended oil is SAE90 but all I could get was 80W-90. Does that really matter?
I did not go from natural to synthetic
I know enough about outboards that they aren't that fragile and it won't fly to pieces when I leave the dock. Also b/c I already ran it from the ramp back home. But long-term--run it through the summer (50 hours or so and a few long hauls) or switch it out sooner?
150 Yam TXRB 2 stroke with a new SEI lower unit (1 1/2 years old)

thanks!

Re: gear oil specs--how important?

Gear oil has specs ranging all over the place: 80-90, 85-95, 85-105, etc. Outboards use marine spec oils because they have extra corrosion inhibitors and probably more anti-foaming agents. But really, I know a number of people who use regular automotive rear-end oil with no ill effects. If your gearcase never leaks, there is no need for the extra corrosion inhibitors.

Now, of course, Yamaha is going to recommend Yamalube at twice the price and it is your choice in what to use.

Change the current new oil? If it makes you feel better! But if your 80-90 is good enough for a 300 horse rear drive vehicle why wouldn't it be OK for your outboard.

BTW: You know this is going to turn into another oil thread with every one posting their opinion. And hopefully a couple of on-line fights for entertainment.

Re: gear oil specs--how important?

I hope so, too. I got beer, you make popcorn. Actually there are a lot of knowledgable people here and much we can learn from them.

thanks for weighing in

Re: gear oil specs--how important?

Boy ain't that the truth. The only time I would use the manufacturer's recommended oil is during warrany. When its up, use whatever else. They may tell you that you voided the warranty.

Re: gear oil specs--how important?

When I saw HC's post, I thought what a good question. I fired up Google and began the quest. Yamaha, Merc, etc. say they make the best ever, no real info. I checked SEI and other than them saying change the lube after a 20 hour break-in with 100 hour changes thereafter, not one word about what to use. Maybe the SEI installation instructions say something.

Has anyone ever seen marine gear lube certification/specs?

TC-W3 two stroke and FC-W 4 stroke certs are all over the Net, but not a word about gear lube. The manufacturers talk about the unnamed additives that make their lube better than the competition, but again, not a peep about marine specs. GL-4 and GL-5 come up, but those are auto ratings dependent on the metals used in the gear case. The GLs are still the basis for marine gear lube with additives for handling water intrusion.

What a way to spend a rainy day at the start of boating season trying to figure out an oil question. :facepalm: I should have made opcorn:

Re: gear oil specs--how important?

good thought on checking SEI; I'll see if I still have the instructions. I assumed they would just follow Yamaha's recommendation since it's a copy.

I am way past my break-in and did all the right stuff at the time (the 20 hour break-in was murder! it was in the fall, striper season starting, and I had to go idling around the harbor, had one dicey run crossing the shipping channel. Going slow about killed me!).

Re: gear oil specs--how important?

Last time I bought a couple tubes of Yamilube it cost me only a few dollars more than the tubes sold by Wallyworld, which was either Lubriplate or Pennzoil or the like. In other words it was less than the cost of the beer i drank while doing the job.

I can see if you were unprepared and neded something quick and the Yami dealer was closed or something. But, what;s the big deal about a couplabucks?

Re: gear oil specs--how important?

GA_Boater said:

Has anyone ever seen marine gear lube certification/specs?

Click to expand...

Each company has their own requirements.

For those that love to quote online about the Magnuson-Moss Warranty Act where they have to give you free product, those same folks are suddenly very quiet when it comes to lower unit oil. Both Mercury and Johnson-Evinrude state to ONLY use their own respective gear oils and do not give any substitute specifications.

There was an independent test of various gear oils a while back where they were tested with and without water in them. Some who tested good in one situation but then finished dead last with a different test environment. It was done by Bass and Walleye Boats Magazine.

Re: gear oil specs--how important?

seahorse5 said:

Each company has their own requirements.

For those that love to quote online about the Magnuson-Moss Warranty Act where they have to give you free product, those same folks are suddenly very quiet when it comes to lower unit oil. Both Mercury and Johnson-Evinrude state to ONLY use their own respective gear oils and do not give any substitute specifications.

There was an independent test of various gear oils a while back where they were tested with and without water in them. Some who tested good in one situation but then finished dead last with a different test environment. It was done by Bass and Walleye Boats Magazine.

Click to expand...

In other words - no. Right? NMMA doesn't certify lower unit lube is all I can gather. Unlike everything else in a boat.