Quicksilver 80w-90 for lower unit F115?

[rocket350]

I'm not starting to start a philosophical debate on oils but I have 2 quarts I still have from my old boat and was wondering if it's ok to use in my 2004 F115 lower unit. Thanks.

[boscoe99]

If marine rated oil I would have no problems whatsoever using it.

[mn808gade]

the gearcase will never know it-th

[rodbolt17]

as long as its NOT a full synthetic GL-5, and marine rated,run it.

[bajakeith]

lwr end oil

my CDI gearcase filler stay's full of quicksilver premium (cool blue) and I use on almost everthing cept. electric shift omc's and some Volvo I/O's that get the GL or mobil one ....

[DennisG01]

as long as its NOT a full synthetic GL-5, and marine rated,run it.

my CDI gearcase filler stay's full of quicksilver premium (cool blue) and I use on almost everthing cept. electric shift omc's and some Volvo I/O's that get the GL or mobil one ....

So this had me wondering. The blue-ish colored Merc stuff is synthetic. But it sounds like the synthetic SHOULD NOT be used in Yamaha's? I see the recommendation above for 4-strokes, and assume that a 2-stroke (like mine) would carry the same recommendation of NOT using synthetic?

[boscoe99]

It is not a synthetic versus non-synthetic issue. It is a GL-4 versus GL-5 issue.

Yamaha has very few models for which GL-5 is approved. One of these specifies either GL-4 or GL-5.

For the 99.9% of all other lower units Yamaha suggests that only GL-4 be used.

[DennisG01]

It is not a synthetic versus non-synthetic issue. It is a GL-4 versus GL-5 issue.

Yamaha has very few models for which GL-5 is approved. One of these specifies either GL-4 or GL-5.

For the 99.9% of all other lower units Yamaha suggests that only GL-4 be used.

Ah. That's where my confusion was. I thought GL-5 = Synthetic and GL-4 = Dino oil. I will check on the specs of the Merc Synthetic stuff - I have lot's of that stuff around, but it's not worth damaging the lower unit vs buying the right stuff.

Question... what if it says something like "GL-5, but also backwards compatible with GL-4"? Is it safe to assume that if it mentions anything about GL-5 that I should pass on it?

[99yam40]

Seems like Rod stated before this all has to do with bushings in the lower unit.
Do not use GL-5 in a lower that has a brass bushing anywhere in the lower.

But a search should lead you to that thread

[boscoe99]

Question... what if it says something like "GL-5, but also backwards compatible with GL-4"? Is it safe to assume that if it mentions anything about GL-5 that I should pass on it?

Interesting. I have not seen that yet.

Perhaps something has been done to the formulation that makes it meet GL-5 specifications while not including the stuff that was used in other GL-5 rated oils, that was the suspected trouble maker.

Like so many other things in life, the suggestion to not use GL-5 rated oil in certain gear cases was done to prevent damage to maybe one in a million units. Problem is that it is hard to say for certainty which will be the one in a million. So, Yamaha says don't use it at all. They are taking, for them, the easy way out.

[DennisG01]

Interesting. I have not seen that yet.

Perhaps something has been done to the formulation that makes it meet GL-5 specifications while not including the stuff that was used in other GL-5 rated oils, that was the suspected trouble maker.

Like so many other things in life, the suggestion to not use GL-5 rated oil in certain gear cases was done to prevent damage to maybe one in a million units. Problem is that it is hard to say for certainty which will be the one in a million. So, Yamaha says don't use it at all. They are taking, for them, the easy way out.

I was only 'thinking outloud' - I do not know if it does or does not say that. What I meant to say, more accurately, is that "What if when I look at the bottle, it happens to say..."

However, with the way you're describing things, unless I can find out for 100% that the Merc GL5 will be OK, I'll skip it. I'm not taking chances on something that is too easy to do a "tried and true" way.

[DennisG01]

I finally looked on the back side of a quart bottle of the Merc Hi-Performance (synthetic) gear fluid. It says "Meets API-GL4 Specs" on it. It sounds like this should work? I'm going to double check by calling Mercury and making sure it doesn't have any type of GL5 classification to it. Again, this isn't about NOT wanting to use the Yamaha stuff - I just have such easy access to the Merc stuff.

[Reel Kahuna]

Just a couple of days ago I bought 90wt Quicksilver Marine lower unit fluid. It registered $11.99/Qt. Told the clerk the sign read, "$5.99/qt. He adjusted to the lower price. Went back yesterday and the sign reads, "$11.99/qt" . That seems a little high to me . Good thing I bought 3 qts the other day .

[rodbolt17]

best I recall the GL4 merc HP gear lube was a semi synthetic.

the GL5 Volvo and the Yamaha HD are full synthetics.

I can tell ya a story bout a man named Bill.

he was a close friend and crabber and old .
I took care of him and Naomi,his wife, best I could for 20 yrs or so, both passed in the passed two years .

Bill did not believe in much maint on his F50 that I gave him so I used the Volvo GL5 in the assumption that it would last longer .

about 2 years into it Bill called me about a rattle in the lower.

at disassembly I found the bushing in the fwd gear that rides on the propshaft peeled out.
not wiped or worn simply peeled out.

that's when I found that full synthetic oils and bushings don't get along.
its also why Yamaha says NO GL5 oils unless the lower is specifically rated for it.
I asked at school one year and the instructor got an engineer to answer.
the additives in the GL5 oil can be corrosive to certain bushing materials and the molecular structure of the oil wont properly lubricate bushing.

the fwd gear bushing on the F50 is not on the parts list and you buy a gear.

so if your POSITIVE your unit has NO bushings then run the synthetic GL5 if you wish.
if your not positive I would stick with a GL4.

[DennisG01]

Just a couple of days ago I bought 90wt Quicksilver Marine lower unit fluid. It registered $11.99/Qt. Told the clerk the sign read, "$5.99/qt. He adjusted to the lower price. Went back yesterday and the sign reads, "$11.99/qt" . That seems a little high to me . Good thing I bought 3 qts the other day .

It sounds like they were getting the "regular" Mercury gear fluid and the HP gear fluid mixed up.