Harley Transmission Fluid ?

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So Harley says use Formula +, or a synthetic 20/50 in the transmission. Somewhere along the line I got the idea that a 90 weight gear oil is roughly the same viscosity as a 50 weight motor oil. And there is plenty of people saying that a 75w-90 is thicker than a 50 weight motor oil.

That doesn't seem to be true. If you look at the specs on mobil 1 75w-90 and Valvolines Syn 75w-90 you find that they are no where near a 50 weight on the viscosity chart.

Understanding that the transmission is going to create shear issues with oil. Is that why they recommend a 20/50 syn, but not a 20/50 dino?

Wouldn't a straight weight 50 accomplish the same thing that a thinner gear oil is going to do?
 
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Hey. I just change my fluids in my bike - 2011 FXLH with the 103". I went with all Amsoil lubricants. I talked to the rep, and he recommended 75W110 Gearlube in the tranny. I did a little research, and decided to give it a try. Seems to be working ok so far.
 
Originally Posted By: kasedian
Hey. I just change my fluids in my bike - 2011 FXLH with the 103". I went with all Amsoil lubricants. I talked to the rep, and he recommended 75W110 Gearlube in the tranny. I did a little research, and decided to give it a try. Seems to be working ok so far.


Same here.
thumbsup2.gif
 
Originally Posted By: OnTheFence
So Harley says use Formula +, or a synthetic 20/50 in the transmission. Somewhere along the line I got the idea that a 90 weight gear oil is roughly the same viscosity as a 50 weight motor oil. And there is plenty of people saying that a 75w-90 is thicker than a 50 weight motor oil.

That doesn't seem to be true. If you look at the specs on mobil 1 75w-90 and Valvolines Syn 75w-90 you find that they are no where near a 50 weight on the viscosity chart.

Understanding that the transmission is going to create shear issues with oil. Is that why they recommend a 20/50 syn, but not a 20/50 dino?

Wouldn't a straight weight 50 accomplish the same thing that a thinner gear oil is going to do?

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You're not the only one that has these questions.
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Gear oil is graded on a different scale than motor oil. Yes, 75W-90 gear oil is roughly equivalent to a 20W-50 motor oil.
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There's a virgin oil analysis of the Formula+ out here somewhere and it's something in the 40-50 weight range, with virtually no additives. Not exactly high-tech fluid - but it is representative of many automotive manual transmission lubes (just thicker). Also - take a look at automotive manual transmission lubes and ATFs and they're in the 20 weight range and many folks never change them.

Would a 50 weight motor oil work just as well? Yes, and no. You would probably want a multi-viscosity 50 weight. e.g. 20W-50. Don't ask me how I know this.....

Think about this: All of the Japanese bikes have a shared sump with the crankcase, transmission, and clutch basket. They seem to run many trouble-free miles on 10W-40. Many of the newer Japanese bikes spec 10W-30. Not unusual for a Gold Wing to go 200,000+ miles.

Harley says that you can go 20,000 miles on the transmission fluid change if you use their Syn3. 10,000 on the primary chaincase. Amsoil recommends their 75W-110 gear lube for Harley big twin transmissions. It's probably way overkill unless you like extended drain intervals.

If you're the kind of guy that changes oil in his Harley @ 3k OCI's and the transmission and primary @ 5K OCI's then yes, you could use a dino 20W-50 in all three holes.

We've been running a 20W-50 in Sportster shared primary chaincase/tranmissions for years. Used to use Castrol but last several years have been using the Valvoline VR1 Racing 20W-50.

On the big twins I like Rotella or Delvac dino 15W-40 in the primary chaincases and have been using Mobil 1 75W-90 LS in the transmission because this is the combination (for me) that gives me the smoothest shifting. ALTHOUGH - I do have a Dyna that I've run Mobil Delvac (dino) 15W-40 in the transmission and in the primary chaincase for the last five years. It shifts slicker than you-know-what.... Don't run this in the others because they don't shift as slick with this combination.

Note that some use B&M Trickshift in their transmissions. I'm thinking this is in the 20 to 30 weight range? Some use it in the primary chaincase as well. I (personally) think it's a bit thin for that application.

Random thoughts by Kevin. Your mileage can (and will) vary.
 
While the Harley trans is about as close to bullet proof as it can get, the biggest issue I ever hear about them are seal leaks. And given the different types of lubes people seem to use in them, it appears you could run straight 50 wt, 20/50 wt, 75/90 wt, 75/250 wt oils and they won't notice the difference. Syn 3, mobil 1 v twin, and amsoil 20/50 wt oils have a Gl-1 rating which seems to be what Harley says their trans needs to be happy. That is the minimum rating an oil needs to have. A 75-90 wt gear oil is probably overkill, but won;t hurt anything as proven by thousand of happy users.Gear oils with 75/90 wt ratings and higher, are made for trans or rear end use specifically so there's not much in their detergent package. All oils are subject to shear forces, some hold up better then others when used in transmission only applications vs engine and transmission applications. Motorcycle specific oils even Harleys oil don't have an API symbol on their bottle. But state their oil meets or exceeds api standards.To me that means there is no standard they ever have to meet, so close enough is close enough.,,
 
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Quote:
Amsoil recommends their 75W-110 gear lube for Harley big twin transmissions. It's probably way overkill unless you like extended drain intervals.



This is not true. The first recommendation from Amsoil is 20w-50 Engine oil, the same as Harley..Then it's 75w-110 and 75w-90.

Currently running Amsoil 75w-110 in my 2011 FLHTK with no issues..
Schaeffers 20w-50 7000 in Engine and RedLine MTL in Primary.
 
Originally Posted By: kballowe
If you're the kind of guy that changes oil in his Harley @ 3k OCI's and the transmission and primary @ 5K OCI's then yes, you could use a dino 20W-50 in all three holes.

We've been running a 20W-50 in Sportster shared primary chaincase/tranmissions for years. Used to use Castrol but last several years have been using the Valvoline VR1 Racing 20W-50.

Random thoughts by Kevin. Your mileage can (and will) vary.



I might Just pour in the VR1 on the next change then and see how it goes from there. It sounds as though it would meet the minimum requirements for lubrication, but may not be the most desireable for shifting.
 
Originally Posted By: rossn2
Quote:
Amsoil recommends their 75W-110 gear lube for Harley big twin transmissions. It's probably way overkill unless you like extended drain intervals.



This is not true. The first recommendation from Amsoil is 20w-50 Engine oil, the same as Harley..Then it's 75w-110 and 75w-90.

Currently running Amsoil 75w-110 in my 2011 FLHTK with no issues..
Schaeffers 20w-50 7000 in Engine and RedLine MTL in Primary.


Oh, you mean the part about it not being recommended 1st in their list?
If you want "gear oil" then the 90W-110 IS their recommendation.

21.gif
 
Originally Posted By: rossn2
Quote:
Amsoil recommends their 75W-110 gear lube for Harley big twin transmissions. It's probably way overkill unless you like extended drain intervals.



This is not true. The first recommendation from Amsoil is 20w-50 Engine oil, the same as Harley..Then it's 75w-110 and 75w-90.

Currently running Amsoil 75w-110 in my 2011 FLHTK with no issues..
Schaeffers 20w-50 7000 in Engine and RedLine MTL in Primary.


Of the three Harley owner's manuals that I have... recommend Formula+ - but say that you can use the SYN3

2008 FatBoy
2009 FXDB
2010 FXDC

I wasn't aware that Harley was recommending SYN3 over the Formula+ in the big twin transmissions and primary chaincases?

Can you give me a link where I can go and look that up?

Tanks

Kevin
 
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I've been 'round and 'round with trans fluids. Just my 2 cents here...I've used gear lube (Mobil 1 75W/90) in my trans and for the first 500 miles or so I was in heaven with butter smooth shifts and quiet and no clunking. Then..back to clunking as usual with a big twin trans. I then went to Formula + and the results were very good as well...lasting about 2000 miles before getting notchy and clunky shifts. Now I am using Redlines VTwin trans and primary lube. So far, at 3100 miles it is still performing well and I'll be happy if it goes 5k miles. If it is still quiet and good at 5k then I will go longer.

Summary - the gear oil didn't impress me. Of course I only tried Mobil 1 and maybe a thicker version or another brand would have done better. The Formula+ is probably the ONLY lubricant I would ever buy from HD and it performed fine for the most part. But, for now - Redline is my lube of choice. I first started using it in the motor - now it's in all 3 holes. This test was performed on my Softail Deuce Twin Cam 88.
 
Did you try the Mobil 1 75W-90 "LS" ?

I found that one to be smoother, longer than the regular M1 75W-90

???

On my Japanese bikes, it seems that no matter which oil I use... they get clunky around 3,000 miles or so.

Nice and smooth with a FRESH oil change. Doesn't seem to matter which oil is used.
 
Originally Posted By: kballowe
Did you try the Mobil 1 75W-90 "LS" ?

I found that one to be smoother, longer than the regular M1 75W-90

???

On my Japanese bikes, it seems that no matter which oil I use... they get clunky around 3,000 miles or so.

Nice and smooth with a FRESH oil change. Doesn't seem to matter which oil is used.


Yes, I used the version with the limited slip (LS) additive in it. You are right though, no fluid is going to last forever.
 
Originally Posted By: clarkg1124
Call me old-fashioned,but I have always used gear oil in the transmission.I started using 75W140 M-1 several years ago,and have always had good performance from it.
Clark



That is not old fashioned. That's called using what works for you...and it works for a lot of people. The Redline fluid I use is really just an enhanced version of their "shockprrof" gear lube. I just didn't get as good of a use (meaning mileage) as I do the Redline.
 
I use either Mobil V-Twin 20W-50 synthetic or Redline 20W-50 V-Twin synthetic in my 103 Harley RKC motor and the Redline V-Twin Primary synthetic fluid in the primary and Redline V-Twin synthetic gear oil with Shockproof in my transmission. Used the same combination in my previous Harley 96. This combination seems to work very well!
 
Originally Posted By: Climb14er
I use either Mobil V-Twin 20W-50 synthetic or Redline 20W-50 V-Twin synthetic in my 103 Harley RKC motor and the Redline V-Twin Primary synthetic fluid in the primary and Redline V-Twin synthetic gear oil with Shockproof in my transmission. Used the same combination in my previous Harley 96. This combination seems to work very well!


That is the combination I've been using for the past 2 years.
 
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