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What gear oil do I need?

B

Beagleman

Regular Contributor
Good day folks. You guys are so awesome that I decided to hit you up for advice again. I got a 40 hp mariner (40 E 6E9 s 104752), 1985 2 cylinder outboard. Basically a copy of those old Yamaha fm series.

It's time to change the lower unit oil. SO, can someone tell me what type of oil, and how much of it I need to pick up, please and thanks? Also, could someone let me know if there's a substitute that's not as expensive (ex: could I use rear end oil from a pick up, ATV, etc?

Sorry for the dumb questions, i'm not that mechanically savy with these outboards.

Thanks for any help.

Robby:confused:
 
SAE 80W90 Gear Lube is recommended for lower units for outboards below 75 horsepower. As long as it is branded for "Marine Use" just about any brand will work. It needs to say "Non-Foaming" type. Check the oil level before draining to see if it is full then use a measuring cup to capture what drains out. A liter will provide several oil yearly changes.
 
do not use automotive gear lube as guyjg said. marine lower unit lube has special anti-foaming agents added. if you use regular gear oil , you will blow out the seals. wal-mart carries a generic brand that is only 5 - 6 dollars for a quart.
 
dtoole said:
do not use automotive gear lube as guyjg said. marine lower unit lube has special anti-foaming agents added. if you use regular gear oil , you will blow out the seals. wal-mart carries a generic brand that is only 5 - 6 dollars for a quart.
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Hey, thanks you guys.

SO, I can get the good gear oil at walmart? How much do I use (does my lower unit safely take)?

THanks for your help.

Robby:confused:
 
I've use Walmart 85-115 gear oil in all kinds of Mercs LUs for years without any problems. It comes in a blue bottle called Super Tek (or something similar).

Jeff

PS: ALL gear oils contain anti-foaming additives. The main difference between this oil and "marine" oils is pricing.
 
Hey thanks guys, that's real helpful. How much oil does my lower unit actually take (as in quantity wise)?

Hey fastjeff, what do you mean by 85-115? as in SAE 85 W 115? And not that I don't believe you, I'm just wandering why companies charge more for marine grade stuff?

Thanks for any future and previous help guys.

RObby
 
fastjeff said:
I've use Walmart 85-115 gear oil in all kinds of Mercs LUs for years without any problems. It comes in a blue bottle called Super Tek (or something similar).

Jeff

PS: ALL gear oils contain anti-foaming additives. The main difference between this oil and "marine" oils is pricing.
Click to expand...


Hey thanks guys, that's real helpful. How much oil does my lower unit actually take (as in quantity wise)?

Hey fastjeff, what do you mean by 85-115? as in SAE 85 W 115? And not that I don't believe you, I'm just wandering why companies charge more for marine grade stuff?

Thanks for any future and previous help guys.

RObby
 
Any gear oil that has a "GL-5 or GL5" rating is suitable for outboard lower units. That rating means that it will not foam if it comes in contact with water. It is marketed in a couple of specific products, notably "off road" gear oil (targetting the "mud bogger's" etc) and "marine" gear oil.

In either form they (the mfg or the company purporting to sell it) crank up the price figuring that owners of such machines will chuck extra bucks to protect their toys.

However, if you look at MOST of the gear oils out there now they are ALL GL5 rated oils, which means that just about any gear oil is suitable for use in your lower unit (provided it has the GL5 rating along with the two dozen other aphabet soup letters in the fine print on the back of the bottle).

In that 40 horse you could use straight 80 weight, 90 weight, 80/90 weight or even the 85/15 weight such as Jeff uses.

The "W" in an oil rating means that it is rated for "winter" use (so it has some additive to prevent crystallization of moisture, trapped in the oil, in sub-freezing temperatures - not normally encountered with outboards -but would not cause a problem either).

The bottom line is you can use "regular" Walmart gear oil (which is GL5 rated), you can pay the slight premium for Walmart's "marine" oil which I suspect is their "regular" gear oil in a different bottle, or you can go extreme and pay upwards of 3 times as much for Merc branded (or even more extreme with "royal purple") and get exactly the same protection.

At the end of the day, even using the cheapest oil available, if you change it once a year or every 100 hours, whichever occurs first, the gear oil will never be the cause of an issue with your lower unit....
 
So many random answers on here. Mercury Premium Gear Lube is what you want. It's their non synthetic gear lube. End thread.
 
galamb said:
Any gear oil that has a "GL-5 or GL5" rating is suitable for outboard lower units. That rating means that it will not foam if it comes in contact with water. It is marketed in a couple of specific products, notably "off road" gear oil (targetting the "mud bogger's" etc) and "marine" gear oil.

In either form they (the mfg or the company purporting to sell it) crank up the price figuring that owners of such machines will chuck extra bucks to protect their toys.

However, if you look at MOST of the gear oils out there now they are ALL GL5 rated oils, which means that just about any gear oil is suitable for use in your lower unit (provided it has the GL5 rating along with the two dozen other aphabet soup letters in the fine print on the back of the bottle).

In that 40 horse you could use straight 80 weight, 90 weight, 80/90 weight or even the 85/15 weight such as Jeff uses.

The "W" in an oil rating means that it is rated for "winter" use (so it has some additive to prevent crystallization of moisture, trapped in the oil, in sub-freezing temperatures - not normally encountered with outboards -but would not cause a problem either).

The bottom line is you can use "regular" Walmart gear oil (which is GL5 rated), you can pay the slight premium for Walmart's "marine" oil which I suspect is their "regular" gear oil in a different bottle, or you can go extreme and pay upwards of 3 times as much for Merc branded (or even more extreme with "royal purple") and get exactly the same protection.

At the end of the day, even using the cheapest oil available, if you change it once a year or every 100 hours, whichever occurs first, the gear oil will never be the cause of an issue with your lower unit....
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Excellent correct answer from someone who is either an engineer or inside industry person that understands how companies use brand marketing to up-sale the same product at a higher price to unsuspecting customers who only want to use "the best" to protect and maintain their expensive new boats.
 
Above info is not completely correct as the auto oils are for gearcases vented to atmosphere. There are differences between auto and marine oil as they are not the same product up branded
 
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