Question about gear oil

[496 Cubic Inches]

I have a 2004 Yamaha 50hp,that I need to change the gear oil in. I've had the motor for almost 2 years,and this is the first time I've changed the gear oil myself. The first two times the dealer did it for free,as part of the sale price of the motor.<br /><br />The manual calls for Hypoid 90 gear oil,but all I can find around town is Hi-Vis 80w-90. The guys at the boating store say it will be fine,but they can't back up there reasoning with anything other than "well their both 90 weights" <br /><br />I'd actually like to know what the difference is between Hypoid 90 and Hi-Vis 80w-90? <br /><br />The next question is about synthetics.I run synthetic fluids front to back in all my vehicles,and would like to run a synthetic gear oil in my boat as well.<br /><br />What is the synthetic equivelant of Hypoid 90 gear oil?<br /><br />You guys have a great site and I'm glad I stumbled across it.

 

[Vlad D Impeller]

Re: Question about gear oil

I could'nt tell ya anything about oil, my knowledge is somewhat deficient in such techinicalities, BUT.. i'm sure that the oil doc or his nemisis will be along in good time, so hang in there for a while, and welcome to the iboats forum

 

[dajohnson53]

Re: Question about gear oil

I believe "hypoid" refers not to the oil itself, but to the type of gear that the oil is to be used for, the type of gear in a differential or lower unit type of thing - you know, where there's right angles involved?<br /><br />Just did a quick check to jog my memory and found this website which talks about the gears and the oil (not necessarily outboard, but same principles, I believe)<br /><br /> http://yarchive.net/car/hypoid_gear_oil.html <br /><br />The 80W90 designation is similar to your car's motor oil. Lower numbers are "thinner". The first number (80) is the viscosity when cold, the higher number (90) when warm.<br /><br />Beyond that, I'd look for some labeling that it's for marine use (as opposed to regular old rear end gear oil). I think there's additives to make it more suitable for potential water contminiation.<br /><br />Bottm line is that I really do not know if 80W90 is functionally the same or better than straight 90, or, if your engine has some hard and fast need for straight weight 90 or if 80W90 is OK. Its just that I would be very surprised if *any* modern oil labeled for marine lower units was not suitable for all lower units. But, with a new engine, I'd really go by the manufacturer's exact specs when in doubt. Look to see if there's some specific rating they list other than the "hypoid".

 

[BoatBuoy]

Re: Question about gear oil

Hypoid 90W gear oil is typically what your automotive garage has to replenish your differential and straight-shift transmission. I used it in lower unit of '57 35hp Johnson and bought it by the quart for nearly nothing from corner garage.

 

[DJ]

Re: Question about gear oil

On an engine as new as yours. I'd use the stuff from the Yammie dealer.<br /><br />Why risk it?

 

[496 Cubic Inches]

Re: Question about gear oil

Originally posted by DJ:<br /> On an engine as new as yours. I'd use the stuff from the Yammie dealer.<br /><br />Why risk it?

The dealer I bought my Yamaha from doesn't isn't a Yamaha dealer anymore,they sell Hondas and Mercs. They push Lubrimatic products,and I've heard that Lubrimatic isn't all that great. I'd like to find something better.

 

[LubeDude]

Re: Question about gear oil

Ok, here goes the old "Neck" again. I love doing that, sticking my neck out that is. <br /><br />I am, (as most here know), an Amsoil fan, have been for a long time. Now I have been using the regular Amsoil 75W-90 regular Synthetic gear lube for about 25 years in one outboard or another with excellent results. Its lighyears ahead of any regular marine gear lube. Yes, they have a marine gear lube, and have just recently came out with a new one that will lube fine with as much as 10% water in it. But I still use the regular gear lube, because I dont want to have every product they have lying around. Way back before they had a marine oil, I contacted them and they told me that nearly any synthetic gear oil would have better properties than a regular gear lube for marine applications and to use there regular 75W-90. So, if you want to buy Marine gear oil, be my guest, but regular synthetic gear lube by any manufacture will do you fine. Plenty of anti foaming and moisture protection.

 

[dajohnson53]

Re: Question about gear oil

Originally posted by LubeDude:<br /> ... I have been using the regular Amsoil 75W-90 regular Synthetic gear lube for about 25 years in one outboard or another with excellent results. Its lighyears ahead of any regular marine gear lube. ...

Asked as an honest question - do you have any information, that what you've posted is true? I mean "light years"?? I'd doubt it is significantly better at all - give dilligent use of a proper marine gear oil and normal-grade consumer (often hard) use - let alone "light years." But I'm open to some information rather than rah-rah opinions. Now if you'd said "... I think it's better." I wouldn't be ragging on you, but you're writing to a guy (OP) who might actually believe this is a fact rather than an opinion the way you stated it.<br /><br />

I contacted them and they told me that nearly any synthetic gear oil would have better properties than a regular gear lube for marine applications and to use there regular 75W-90. ... [/QB]

This has to be tongue in cheek - that a statement by a manufacturer's rep (the guy you talked to) is giving unbiased info. I understand you are loyal to and love Amzoil, and I understand he was talking about synthetics in general (but they are a seller of synthetics, so it's self serving)... but "where's the beef?" Surely you wouldn't expect a synthetic oil company to say "oh, just buy any gear oil that meets the manufacturer's specs. our stuff really isn't any better even though it costs 3X more." It gives the discussion absolutely nothing of value. I'm open to more information and would appreciate it.

 

[LubeDude]

Re: Question about gear oil

Ok, I will admit to being a bit "Over zellous at times. How about if I just say its a lot better IMHO. The other statement about the gear oil being OK to use I have to stick by. I didnt tell him "NOT" to use a Marine gear oil. I basically told him what I do.

 

[dajohnson53]

Re: Question about gear oil

I know - and I was really just kind of yanking your chain about the "light years" thing Really I won't argue about whether synthetic is better or not. There's no reason to think it isn't (or is, without some studies looking at the actual application one is dealing with). In fact, I frequently use it in my cars when it's really cold because I do believe, if nothing else, it flows and lubes better when really cold. For that specific application, I do think it's better. But that doesn't mean I think it's better for normal use. <br /><br />But you did say: "I contacted them and they told me that nearly any synthetic gear oil would have better properties than a regular gear lube for marine applications and to use there regular 75W-90"<br /><br />Which I understand you to be saying: the Amzoil guy said synthetic oil made for regular (not marine) gear applications is better than any dino marine gear oil. That's the statement I'm skeptical about - it may or may not be factual. I certainly put no believability into it just because it was said by a rep. of a company that sells only synthetic oils. That,to me, would be just plain silly. There's no doubt in my mind that my personal bias would be just the opposite to what you said - that any marine- specific gear oil (dino or synthetic) would be better than any gear oil (dino or synthetic) that is not marine- specific. ... until proven otherwise - not by some company rep, but by actual studies that speciically relate to normal use in a marine lower unit application. <br /><br />Please, I'm not doubting Amzoil is a good quality product - I have no idea either way. But I am skeptical about that particular statement.

 

[LubeDude]

Re: Question about gear oil

Originally posted by D.:<br /> But I am skeptical about that particular statement.

Hey, I dont blame you a bit!<br /><br />Marine gear oil is really no more than a regular gear oil with a slightly different additive package. Years ago, outboard manufactures specified regular gear oil, same thing cars and trucks used. Now everything has to be aplication specific. (Not necesarily a bad thing).<br /><br />The extra additives used in marine gear oil are there to lower the amont of foaming, (Small gear case), Improved protection if there is water present, thats basically it in a nut shell.<br /><br />All synthetic lubricants have excellent antifoaming properties, and they have excellent moisture control as well. I always see an RPM difference when I change someones lower unit over to a synthetic, more noticable in a large engine, (V6s), So there is either much better lubrication, or this happens because the lube is physicly thinner. My thoughts on it are also that the lower unit is (Where?) in the water, so it is always cold and the synthetic allows things to move better so it free's up some HP. Ive never had anyone not comment to the effect that there is a little more RPM at WOT after the switch, even if it wasnt Amsoil. <br /><br /> Honestly, I should recommend a Marine gear oil just so I dont confuse people and Im guilty of not doing so. I used to run a disclaimer at the bottom of my posts stating that I have no profesional background in lubrication and that the things I say are just opinions. Maybe I should put it back on.<br /><br />I use the Amsoil 75W-90 in every outboard I have ever had, but I am very dilligent about checking and changing it, not everyone is.