Why 75w90 in tranny?

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Why 75w90 in tranny?

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Why 75w90 in tranny? - 3/17/2008 7:43:06 PM

gman66

Posts: 25
Joined: 6/20/2007
Status: offline I just bought 6 quarts of Amsoil 20w50 for my RKC and it says to use in all 3 holes. A lot of people are recommending 75w90 severe gear for the tranny. Will I be ok with the 20w50 or should I switch and why? Thanks

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RE: Why 75w90 in tranny? - 3/17/2008 7:48:02 PM

KBFXDLI

Posts: 7563
Joined: 2/4/2006
From: Cleveland, Ohio USA
Status: offline
Save the 20w50 and get some amsoil 75w90 or 75w110 severe gear for your trans. Don't worry that 20w50 won't go bad on the shelf. A motor oil in a trans will shear out of grade faster then a gear oil. Plus gear oil will give you better & smoother shifting and quieter operation. I would get the 75w110 myself if you like amsoil.

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(in reply to gman66)

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RE: Why 75w90 in tranny? - 3/17/2008 7:54:30 PM

gman66

Posts: 25
Joined: 6/20/2007
Status: offline Thanks for the advice. Why the 110 over the 90. Any specific reason

(in reply to KBFXDLI)

Post #: 3

RE: Why 75w90 in tranny? - 3/18/2008 4:39:15 PM

rbabos

Posts: 1313
Joined: 3/16/2007
Status: offline Thicker when hot.
Ron

(in reply to gman66)

Post #: 4

RE: Why 75w90 in tranny? - 3/18/2008 6:26:39 PM

smitty901

Posts: 366
Joined: 2/3/2008
Status: offline
No to same stuff in all holes amsoil or not
http://www.hdtalking.com/ look around oils and lube do your home work

(in reply to rbabos)

Post #: 5

RE: Why 75w90 in tranny? - 3/18/2008 7:12:17 PM

KBFXDLI

Posts: 7563
Joined: 2/4/2006
From: Cleveland, Ohio USA
Status: offline

quote:

ORIGINAL: gman66

Thanks for the advice. Why the 110 over the 90. Any specific reason

When it gets hot it has more viscosity improvers to thicken it to a 110w vs a 90w. I use the Redline Shockproof Heavy (75w250) and it quiets trans noise and gives you better protection at higher heat ranges. The 75w110 will give you great performance.

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Our contest is not only whether we ourselves shall be free, but whether there shall be left to mankind an asylum on earth for civil and religious liberty. Sam Adams

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RE: Why 75w90 in tranny? - 3/19/2008 6:59:27 AM

smitty901

Posts: 366
Joined: 2/3/2008
Status: offline
If you can not get Spectro GL5 for the 6 speed the REDLINE is the one I use because spectro to hard to get Moto oil does not belong in gear box
quote:

ORIGINAL: KBFXDLI

quote:

ORIGINAL: gman66

Thanks for the advice. Why the 110 over the 90. Any specific reason

When it gets hot it has more viscosity improvers to thicken it to a 110w vs a 90w. I use the Redline Shockproof Heavy (75w250) and it quiets trans noise and gives you better protection at higher heat ranges. The 75w110 will give you great performance.

(in reply to KBFXDLI)

Post #: 7

RE: Why 75w90 in tranny? - 3/20/2008 10:50:26 AM

pete913

Posts: 146
Joined: 5/24/2007
Status: offline
I'd use the 20W50. Look on the bottle, it meets GL1 specs, which is all that trans needs. Extreme pressure additives are only necessary in hypoid gear setups, and there's no advantage in using them in a transmission.

(in reply to smitty901)

Post #: 8

RE: Why 75w90 in tranny? - 3/20/2008 10:55:38 AM

lecomte38

Posts: 394
Joined: 11/12/2007
Status: offline cause it shifts soooo smooooth. I might go back to 20/50 just to get that classic Harley CLUNK.

(in reply to pete913)

Post #: 9

RE: Why 75w90 in tranny? - 3/20/2008 11:56:52 AM

roxo56

Posts: 9
Joined: 10/9/2006
Status: offline Just did 5k oil change and did tranny too. Used Royal Purple 75w-140. A little quiter, not much. Still got a "clunk". No more whining, though. Next change I'll switch over to Redline shockproof.

(in reply to lecomte38)

Post #: 10

RE: Why 75w90 in tranny? - 3/21/2008 8:12:29 PM

cHarley

Posts: 3751
Joined: 2/14/2007
From: Boynton Beach, FL
Status: offline If you wouldn't put Gear Oil in your engine, why would you want to put Engine Oil in your gearbox?

FYI: HD no longer recommends the "One Oil in All Holes" BS as the best option. They now just say it's OK to do.

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RE: Why 75w90 in tranny? - 3/21/2008 11:15:26 PM

WaterBuffalo

Posts: 142
Joined: 1/14/2007
Status: offline Amsoil says that the 20w50 is better in your tranny than the severe gear. unless you have one of the newer bikes with a 6 speed.

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Post #: 12

RE: Why 75w90 in tranny? - 3/22/2008 9:15:21 PM

gdkenoyer

Posts: 126
Joined: 6/2/2007
Status: offline Besides the search, you might scan thru the sticky topics at the beginning of this forum, specifically:
- Engine Oil vs Gear Oil
- What TRANS oil do you use?

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Post #: 13

RE: Why 75w90 in tranny? - 3/23/2008 9:08:48 AM

EVOrider

Posts: 1160
Joined: 2/13/2007
Status: offline If someone chooses to use 20w50 in the transmission....so be it, it is YOUR bike.

Gear lube with a GL-5 rating was originally designed for the Harley transmission. Brand, synthetic, non-synthetic, blend, or even grade is not a major concern here.

If I were to develop a major leak all of a sudden out in the middle of nowhere and no fix was viable. Gear lube was not to be found, but the bike still had to be ridden....then I would use just about any motor oil that was available at the time. I'll use a motor oil in an extreme circumstance in the transmission.

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Post #: 14

RE: Why 75w90 in tranny? - 3/26/2008 4:19:05 PM

scott63

Posts: 57
Joined: 1/30/2006
Status: offline From Spectro regarding GL1/GL5 oils.

With motorcycles, gear oil, tranny oil..... same difference. GL-1 usually is the formulation for these applications, meaning it is OK to use in a wet clutch or with bronze bushings or synchro rings. This oil will not have the sulphur smell.

Differential oil, that would be a Hypoid GL-5. Some automotive people use the term 'Gear Oil' exclusively referring to a hypoid differential oil. This oil has the sulphur smell.

The GL-5 is OK to use, but the downside to a GL-5 is that it will eat rubber, so if the seal on the gearbox output shaft ever went south, the oil could damage the drive belt.

This is why HD uses a GL-1 at the factory and why we recommend our Heavy Duty Platinum Gear Oil, 75w140, which is a full synthetic GL-1.

Our Heavy Duty Gear Oil 85w140 is a petroleum-based GL-5 Hypoid oil and is also considered a differential oil, and is designed for the Big Twin chain drive bikes. Our new Heavy Duty Platinum 6-Speed Full Synthetic Gear Oil is also a GL-5 made exclusively to work with the helical cut gears on the new 6-speed gearbox. This oil is also in the differential oil category.

You can use any of these oils in your Fat Boy, but, there is a microscopic chance that if an oil leak developed in that output seal while using the GL-5, you would need to park it before you ruined your drive belt.

http://www.spectro-oils.com/motorcycle/cruiser/tech.asp?action=v&id=33

(in reply to EVOrider)

Post #: 15

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