Lower unit question

littledog · **Posted:** Tue Nov 28, 2017 11:23 am

In my attempt to winterize a Mariner 4 hp.....I didn't see Marine Lower Unit oil... type C, at Canadian Tire....may have missed it?..............ended up with a $6 bottle of Motormaster Extreme Pressure Gear oil SAE 85W-140(meets requirements for HYPOID+other gear types)I'm thinking this is fine, am I wrong?

Also , on line I see what appears to be smaller bottles of lower unit oil for $50 $60 on line.....seems expensive? what should I be using, and paying to replace the oil in an older,small hp lower unit.....sorry I'm not a fishing report, thanks for reading

Roblin · **Joined:** Mon Jan 12, 2015 6:53 pm **Posts:** 842

My thought is that the viscosity rate on the oil you bought is pretty high. The motors I've had call for SAE 90. I would think that SAE 80w90 would be OK because it's pretty close.

Cobourg CTC has Quicksilver Premium Gear Lubricant, 1-L Product, #028-1764-2, $14.99. It doesn't give the viscosity but it's made for Mercury/Mariner lower units.

The website shows 4 in stock at the Cobourg store.

littledog · **Posted:** Tue Nov 28, 2017 1:05 pm

Thanks Roblin ,I'll do another Canadian Tire trip!

Grizzly · **Posted:** Tue Nov 28, 2017 5:08 pm

quick silver meets or exceeds any oil out there and recommended by dealers everywhere at least any dealer I've ever known anyways lol what you put in sure wont hurt it if in doubt leave it over winter then drain it before running it next season wont hurt a thing......... I've known guys who drain lower units empty and store it all winter with no fluid in it at all .

dani · **Joined:** Thu Jan 13, 2011 9:03 pm **Posts:** 54

"I've known guys who drain lower units empty and store it all winter with no fluid in it at all ." That's playing it safe if ever there was water in the lower unit. I either drain it or change it and yes Quick Silver is great.

Walleye 9 · **Joined:** Mon Jan 24, 2011 12:05 pm **Posts:** 1985

Just curious...what do guys do that keep their boats out till the end of December or till first ice?? The air temps will have dropped below zero several times in that time period. About 3 weeks ago we had a cold front come through and the temps dropped to about -10C overnight. I doubt they are draining the bottom end after everyday of fishing. I drain mine every year before storage, but just wondering if it is really necessary. If there was that much water in there where it would actually freeze and expand enough to crack something, I'm sure you would know about it before that time. Some sort of breakdown or something in the summer months.

Roblin · **Joined:** Mon Jan 12, 2015 6:53 pm **Posts:** 842

You should change your lower unit at the end of the fishing season. If the oil has no water then refill and ready to go in the spring. If your lower unit has water the off season is a good time to change your seals.

I use my motor until the bay freezes. I change the oil my lower unit before it gets real cold. Usually October so the oil will flow. If there's no water then I run the motor until the ice is in.

When I winterize my motor I check the unit for water and if there's none it's good to go. If I have water then I have a winter project.

It doesn't take much water to break a lower unit. You can't really measure water in oil by looking at it so if there's any change it.

25 years ago I froze a lower unit. $1,500.00 will buy 100 bottles of $15.00 oil.

Walleye 9 · **Joined:** Mon Jan 24, 2011 12:05 pm **Posts:** 1985

Roblin wrote:

You should change your lower unit at the end of the fishing season. If the oil has no water then refill and ready to go in the spring. If your lower unit has water the off season is a good time to change your seals.

I use my motor until the bay freezes. I change the oil my lower unit before it gets real cold. Usually October so the oil will flow. If there's no water then I run the motor until the ice is in.

When I winterize my motor I check the unit for water and if there's none it's good to go. If I have water then I have a winter project.

It doesn't take much water to break a lower unit. You can't really measure water in oil by looking at it so if there's any change it.

25 years ago I froze a lower unit. $1,500.00 will buy 100 bottles of $15.00 oil.

So are you saying that if you plan on fishing till the water freezes you should drain the bottom end sometime early fall to make sure there is no water in there, and then change it again before storage?? That is definitely being on the safe side. I'm not trying to be sarcastic here, but I doubt many people do that. There must be a lot of cracked lower units out there, cause like I mentioned earlier, the temps will have dropped below freezing several times before the end of December.

Roblin · **Joined:** Mon Jan 12, 2015 6:53 pm **Posts:** 842

If there's no water infiltration, I only replace my oil once a year in the fall.

I change my oil in the fall for two reasons. The oil flows much easier and I want to make sure there's no water before the cold nights.

I check the oil again when I winterize. I take out the fill screw (leave the oil level screw in) and very little flows out. Water mixes completely through the oil, so a few drops will tell me if I have water.

No water then I replace the filler and done. If I have water then I'll get the seals changed.

Once you break a lower unit your more cautious. I figure taking 5 minutes and pulling a screw for a look is better than spending thousands.

Call me anal if you want.

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Lower unit question

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