Harley Transmission "needs"

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MoreCowbellAz

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I realize Harley lubes are debated ad nauseum throughout the internet, but I really haven't found exactly the info I'm looking for, at least not as far as hard facts go. Just educating myself……I have an 00 Road King with Royal Purple 75w90 in the transmission, no reason other than I was in a hurry and grabbed it while in Oreilly. Works fine. However, I got to thinking about how it's probably way overkill with this low tech transmission (no hypoid gears to my knowledge), if I'm not mistaken HD calls for GL1 which seems stone age. I'm guessing most every modern 15w40 or higher bike or diesel lube would meet or exceed that. I happen to love Rotella 15w40 in all sorts of motors but whatever, I'm not shopping for answers here. So aside from the initial weirdness one feels about putting "engine oil" in a Harley transmission, why not? It's not like there's a lot of high tech needs in that transmission, nor is it a high hp engine that's stressing the drive train. So I'm not seeing the mechanical demands. Looking around the forums typically the reasons given is more or less "cuz there's hi tech lubes out there", or "gear lubes for gears". But that seems like its missing the point, is there an actual benefit that's been tested?

Before I get flamed, I actually did research and I understand the opinions out there, but as much as I researched I never saw anything in the way of hard facts for GL1 transmission needs; all the info seems to be related to the engine, and maybe the primary. To be honest I figured there'd be some renegade out there that for instance ran Rotella in the transmission if for no other reason than to prove "the norm" wrong. But……..nothing.

Last thing…….I never think twice about putting diesel oil in my dirt bike or road race bike, and those bikes all have shared sumps. But for some reason it feels weird to think about doing the same in my Harley, no idea why. Hence, my looking for facts.
 
The transmission and primary share a sump on a Sportster and Harley Syn 3 or Mobil 20W-50 works in that. I think the HDEO would probably be fine.
 
Your bike calls for 20/50 motor oil in the transmission, Dont over think it. its not out of the dark ages, many automobile manual transmissions use/call for or acceptable motor oil as well.

Even Amsoil recommends their standard motor oil in a Harley transmission as best choice above "gear oil"

MOST but not all gear oil is made for differentials, if put in a unit not made for certain gear oils you can overheat some bearings, or end up with leaky seals or possible corrode to some degree (whether is matters or not) some soft metals or sync gears.

Again, you will be good to go, just knowing HD recommends a 20/50 motor oil and again, is and has been used in many automotive transmissions as well, some, now adays market "special" transmission oil, just as Harley would market Primary+ for the transmission but no longer does, as their website simply shows just motor oil now.
Ps, there is nothing wrong with GL1 oil as it serves a purpose in almost every engine made as well as still to this day even standard car manual transmissions.
 
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Harley only recommends "THEIR" oil in their brand of motorcycle.But they do say you can use diesel oil in a pinch. No brand in particular. But no one has had anymore problems with using gear oil in the transmission then if the used Harley's oil. And given the fact most metric bikes use a shared sump system for their oil, using a 15w40 wt oil for the trans and primary should work fine. There's a VOA posted here that show Harley's primary oil is nothing but 50 wt oil with a nothing special additive package, so pretty much any oil will work better.Don't let Harley's scare tactics bully or scare you into paying more for their oil, then you would pay for the more popular oils with better price points.,,
 
Originally Posted By: BigCahuna
But they do say you can use diesel oil in a pinch. No brand in particular. But no one has had anymore problems with using gear oil in the transmission then if the used Harley's oil. And given the fact most metric bikes use a shared sump system for their oil, using a 15w40 wt oil for the trans and primary should work fine.


I saw that about diesel oil in my owner's manual as well, which is what got me to thinking about the 15w40 diesel oil I'm so find of because I saw lots of folks running 20w50 in the trans but I don't think I ever saw anyone talking about running 15w40 there. That's what surprised me, but maybe someone saw some data where a 15w40 was giving up something that a 20w50 didn't.

Just to be clear, I don't mind running gear lube or anything, nor am I looking for reasons to cheap out on the rest of the motor. I'll run whatever lubes all around if the machine needs it regardless of price. What I'm not into is paying for marketing when the fact is something more run of the mill does the same job. Sorta a pet peeve of mine.

Combine that with the fact the Harley, while I do like it for various reasons, it's kind of like "welcome to the 1930's" in a lot of ways design wise. haha It's a strange beast when you're used to dealing with more modern bike technology.
 
When you consider that metric bikes run 15w40 wt oils thru the motor, clutch and trans,and it holds up there. The only part of the puzzle that doesn't match is when run in a Harley Sportster's trans and primary, it doesn't get beat up in the motor. So it doesn't get contaminated with gas and particles of combustion. In a big twin, I run 15w40 wt rotella t in the primary because I feel 20/50 wt which the moco recommends, causes that loud thunk when you shift into 1st gear. I believe it's because 20/50 has more drag to it. I also wouldn't use gear oil in a Sportsters primary because of the added drag on the clutch plates.It's a free country so use what your comfortable with, but have a reason why you use it not just because Tom, **** and Harry use it.,,,
 
Originally Posted By: alarmguy
Your bike calls for 20/50 motor oil in the transmission, Dont over think it. its not out of the dark ages, many automobile manual transmissions use/call for or acceptable motor oil as well.

...


Be interesting to see what a 2000 owners manual says, but my 14 Softail OM and FSM does NOT call for 20/50 motor oil in the trans and primary.

It says Formula + or SYN3 20/50 is the recommended lubricant. Genuine HD360 (Conventional) 20/50 is not listed as an option. The old bike calls for HD260 in the engine and GL1 in the transmission/primary

So Harley Davidson HAS not said "20/50 Oil" is acceptable. They've set up an excellent case in the description of SYN3 as "special", and have not included their own 20/50 conventional engine oil as "recommended".

If a dealer chose to make an issue of this you'd have little leg to stand on if you are using a product "off label" like car oil. If on the other hand the product is recommended by the manufacturer for transmission and primary use the dealer would have little leg to stand on.

I offer for consideration the following:

  • Will a $25 VOA indeed reveal any special properties that SYN3 or Formula + may have?
  • Will additives (such as LS friction modifiers) in a differential gear oil adversely impact the transmission?


Doesn't really matter to me what anyone else does but at least during the warranty period I will be using products that say they are suitable for primary case and/or transmission use.

YMMV and all that...
 
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I guess that's my point and my question I started out with.......mfrs seem to set up their lube X as some special serum for some special transmission, and a lot of users do too. We all want to take care of the internals, but it's not the space shuttle. From a non-engineer point of view this thing screams simple transmission with simple needs, without much going on inside that a basic lube can't handle within a broad range of weights and formulations. Again, a non-engineering pint of view, but that's how it seems when you look at the capabilities of modern oils and a simple mechanical design. That's where my post originally came from, has anyone filled the transmission up with for example a 30w or a 15w40and then observed the performance or had it tested? I thought for sure someone would have with Rotella or something, maybe they're not brave enough to say it. lol

I agree if a warranty is in play then that's a different story, I'm just talking about mechanics here.

I'm going to take a look at my 2000 owners manual tonight and see exactly what it calls for but I seem to recall it just lists an HD part number I've never bothered to look up.
 
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I'd genuinely be interested in the technical answers as well.

Not in my Big Twin, but the sporty has Mobil 1 10w40 in the shared primary trans, right now (4T MC oil though). I'm not sure I like the shifting of it, but it hasn't been in long.

SYN3 in the Softail seemed to improve shifting and clutch action.
 
Originally Posted By: DuckRyder
Originally Posted By: alarmguy
Your bike calls for 20/50 motor oil in the transmission, Dont over think it. its not out of the dark ages, many automobile manual transmissions use/call for or acceptable motor oil as well.

...


Be interesting to see what a 2000 owners manual says, but my 14 Softail OM and FSM does NOT call for 20/50 motor oil in the trans and primary.

It says Formula + or SYN3 20/50 is the recommended lubricant. Genuine HD360 (Conventional) 20/50 is not listed as an option. The old bike calls for HD260 in the engine and GL1 in the transmission/primary

So Harley Davidson HAS not said "20/50 Oil" is acceptable. They've set up an excellent case in the description of SYN3 as "special", and have not included their own 20/50 conventional engine oil as "recommended".

If a dealer chose to make an issue of this you'd have little leg to stand on if you are using a product "off label" like car oil. If on the other hand the product is recommended by the manufacturer for transmission and primary use the dealer would have little leg to stand on.

I offer for consideration the following:

  • Will a $25 VOA indeed reveal any special properties that SYN3 or Formula + may have?
  • Will additives (such as LS friction modifiers) in a differential gear oil adversely impact the transmission?


Doesn't really matter to me what anyone else does but at least during the warranty period I will be using products that say they are suitable for primary case and/or transmission use.

YMMV and all that...


Ummm .. think we are splitting hairs here. Your own post says HD synthetic 20/50 oil in the transmission. So you can use 20/50 in the transmission. Unless one of us is missing something here, we are talking about the same thing. HD DOES recommend 20/50 oil for the Primary, Transmission and engine. SO I am unsure why you are saying HD does not recommend a 20/50 in all three holes when you also state HD recommends there 20/50 in all three holes *L*

Hd says to use their synthetic 20/50 so the door is open to use a 20/50 if you choose another brand.. Which is what I am saying, AND even Amsoil says to use their 20/50 over their own gear lube.

Now if one chooses to use a conventional 20/50 I doubt it will matter one bit but if you choose a syn 20/50 you are choosing what HD recommends.

Also you will notice as posted in here, Primary+ is no longer on HDs website, leaving, again, only 20/50 for all three holes.

All the oils in discussion Primary+, 20/50 syn and 20/50 conventional are GL1 oils and what is recommended not only, again, by HD but even Amsoil above traditional GL4 gear lubes.
 
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Originally Posted By: alarmguy
...
Hd says to use their synthetic 20/50 so the door is open to use a 20/50 if you choose another brand.. Which is what I am saying, AND even Amsoil says to use their 20/50 over their own gear lube.

...


That is two different issues.

NOWHERE in the OM or FSM does it say use 20/50 engine oil. It says SYN3. The 3 in SYN3 is Engine - Primary - Transmission. SYN3 list all 3 on the bottle. HD360 (Conventional) list "Engine".

It may well be splitting hairs, but Harley has said you can use SYN3 - You may extrapolate that to mean "any 20/50 engine oil" or "any syn 20/50 engine oil", but that is not what it says.

If Amsoil says use their 20/50 then that is fine - one must trust that they have tested it.

The dealer was still full of HD360 and Formula + today, so I am not sure what the disappearance from the website means.

See also (direct link to PDF):

Engine Oil FAQS

As a point of order, I make no claim as to any engine oil being ok or not ok, my point is that "Use SYN3 20/50 Engine - Primary - Transmission" does not equal "use 20/50 engine oil".
 
Originally Posted By: MoreCowbellAz

I'm going to take a look at my 2000 owners manual tonight and see exactly what it calls for but I seem to recall it just lists an HD part number I've never bothered to look up.


Ok my 2000 RK manual calls for Transmission Lube part no 98853-96, which I can find almost no info on other than it appears to me 75w90 lube. Must've been that back in 2000 lube was lube, and now we're all enlightened.

So one other question for you folks who know more than I ……….IF in fact all that's called for is GL1 spec, isn't that the barest of the bare bones stuff that just about anything made these days would meet? My understanding is everything below GL4 is inactive these days, but maybe I was misinterpreting the article I was reading.
 
In our previous discussion on formula + we discussed GL5 yellow metal corrosion (and I believe Royal Purple did not do well in that respect) but it was said a Harley transmissions (sportster which is shared primary excepted) did not contain yellow metals.

A quick search of the Harley boards does not really clarify yellow metals but seems to make a distinction in 5 speed and 6 speed.

Clear as mud huh...
 
The RP Max Gear I bought for the transmission says safe with yellow metals, so I assume that is in fact the case. On the other hand, for good or bad I'm one of those that take many mfr statements with a slight bit of skepticism. Just a bad habit I think. So hopefully "safe" does not mean "safe-ish". My transmission seems to like it so far at least, 1500 miles in. BTW I pulled the dipstick the other day and the transmission fluid looked as clear and clean as the day it came out of the bottle. That's what got me to thinking maybe all current transmission lubes are far exceeding the needs of this low tech usage.
 
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Being the trans oil on a Harley Big twin doesn't get contaminated with engine dirt, the oil on everyone I've ever owned looks as clear and clean when I drain it out, as it did going in. If you notice silver flakes in used trans oil, you have something going on and it won't be good.,,
 
Originally Posted By: DuckRyder
Originally Posted By: alarmguy
...
Hd says to use their synthetic 20/50 so the door is open to use a 20/50 if you choose another brand.. Which is what I am saying, AND even Amsoil says to use their 20/50 over their own gear lube.

...


That is two different issues.

NOWHERE in the OM or FSM does it say use 20/50 engine oil. It says SYN3. The 3 in SYN3 is Engine - Primary - Transmission. SYN3 list all 3 on the bottle. HD360 (Conventional) list "Engine".

It may well be splitting hairs, but Harley has said you can use SYN3 - You may extrapolate that to mean "any 20/50 engine oil" or "any syn 20/50 engine oil", but that is not what it says.

If Amsoil says use their 20/50 then that is fine - one must trust that they have tested it.

The dealer was still full of HD360 and Formula + today, so I am not sure what the disappearance from the website means.

See also (direct link to PDF):

Engine Oil FAQS

As a point of order, I make no claim as to any engine oil being ok or not ok, my point is that "Use SYN3 20/50 Engine - Primary - Transmission" does not equal "use 20/50 engine oil".


I won't disagree with anyone who wants to use only what the manual says. Harley only recommends their 20/50 oil in all 3 holes or primary+ in two of them. If you want to use a 20/50. Diesel oil ok in the engine but hard to find except 15w40. I think Amsoil makes a 20/50 diesel. They don't recommend anything else, in fact imply only to use HD oil. S it's a personal choice if one doesn't listen to them.
I think some used oil analysis and VOAs in here show primary plus as just a good solid 50 weight mineral oil with a less robust add. package and why, I would think they now recommend their 20/50 for everything.
 
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Originally Posted By: alarmguy
...Harley only recommends their 20/50 oil in all 3 holes or primary+ in two of them. If you want to use a 20/50. ...


I feel like we are just missing each others point(s).

Originally Posted By: alarmguy
...I think some used oil analysis and VOAs in here show primary plus as just a good solid 50 weight mineral oil with a less robust add. package and why, I would think they now recommend their 20/50 for everything.


I'm not convinced that consumer level used oil analysis/VOA's can tell us that something is just 50 weight mineral oil. In fact there is a discussion in the UOA general forum that says that a $25.00 OA cannot tell a synthetic from a conventional.

Let me try one more time to see if I can clarify my point.

  • If you read the PDF FAQs (which is straight out of the P@A catalog I believe) it holds SYN3 out to be some sort of specially formulated lubricant with properties that make it suitable for use in transmissions and primaries.
  • No such claims are made about Genuine HD360 20/50 (in any grade actually)
  • The OM and FSM say to use either Formula + or SYN3 (I'm not sure what the "primary +" you keep mentioning is.)


So my point is that you cannot automatically assume that any 20/50 oil is fine, nor is it accurate to say "HD says use 20/50 oil" when they actually say "SYN3".

So for instance, if you decide to dump GTX 20/50 in your transmission and roll into the dealer at 18mths and with a blown up transmission I think you've got a problem if the dealer choses to make an issue of it. (That goes for any product that doesn't position itself as suitable.) However if you go in with redline shock proof heavy which (redline says is suitable) they probably will be less likely to make an issue of it, and if they do less likely to prevail.

IMO what makes this a big pain in the rear end is that Harley doesn't give much to go on - they say engine oils should meet HD360 "rating", but don't say anything about trans/primary in my manuals. If they specified MA or GL5 or something it would be easier on us.

To further the confusion, there isn't even agreement in the aftermarket.

Amsoil says 20/50 in all 3 holes
Mobil says V-Twin in Engine, 4T in Primary preferred (V-Twin acceptable) and 75-90 in trans.
Redline calls for 20/50, primary case oil (claimed to be 10/30-75/90 GL4) and shock proof heavy which they claim has a 75/240 film thickness with a 75/90 fluid friction.

It is no wonder there is an argument about this stuff...

Now I feel like we/I have completely derailed the OPs thread and no one has really posted any technical information to support engine oil VS gear oil...

So I'm sure he is still interested in that and I would be as well.

Incidentally I came up empty on that part number in the 2000 owners manual too.
 
Correction on Redline V-Twin Primary Case Oil

API Service Class GL-4
SAE Viscosity Grade (Motor Oil) 5W30
SAE Viscosity Grade (Gear Oil) 75W80
 
I have a Clymer manual and its basically a copy of Harleys manual. And as far as oil goes, it says to use Harley's oil first, or a SAE rated 10w40, 20w50, 50wt,and 60wt oil second.This manual covers years 1999-2005, and does not have any mention of SYN III. I believe Harley came out with SYN III in 2003. As far as the primary and transmission oil goes, it states to use Harley's oil or an equivalent. Every motorcycle specific oil for use in a V-twin motor other then Harley's that I've seen, says their oil meets at least a SG API rating, and a GL-1 rating. So if you had a warranty issue I don't see how in a courtroom Harley could defend their stand to refuse warranty coverage, when they have such open range of specifications. Their own brand of oil doesn't list which of any API spec it meets. Alot of people have paid alot of money to have oils tested and by now there would be a big lawsuit going with labs like Blackstone, if they couldn't tell you what weight any given oil was. And by the test results/numbers they get, if an oil is mineral or synthetic.I guess some people refuse to believe data that is given to them that others accept as being truthful and real,,,
 
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