75W-90 versus 75W-140
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Road Warrior
Joined: Feb 2009
Posts: 1,274
Likes: 130
From: Now Western TN
75W-90 versus 75W-140
OK, before you blast me I did try the search using the title and variants but I got several hundred hits and wading through them would take forever to find the answer.........if it is even in there.
I went to an Indy to buy some Amsoil Sever Gear and he said to use 75W-90 in the tranny but I see a lot of guys on here use 75W-140. So what's the Pro's and Con's between the 2? Do both meet the recommended by Harley? I looked my service manual and it states use HD PART# xxxxxxxx, that didn't do me any good.
I went to an Indy to buy some Amsoil Sever Gear and he said to use 75W-90 in the tranny but I see a lot of guys on here use 75W-140. So what's the Pro's and Con's between the 2? Do both meet the recommended by Harley? I looked my service manual and it states use HD PART# xxxxxxxx, that didn't do me any good.
Road Warrior
Joined: Nov 2008
Posts: 1,955
Likes: 7
From: The Great Northwest
OK, before you blast me I did try the search using the title and variants but I got several hundred hits and wading through them would take forever to find the answer.........if it is even in there.
I went to an Indy to buy some Amsoil Sever Gear and he said to use 75W-90 in the tranny but I see a lot of guys on here use 75W-140. So what's the Pro's and Con's between the 2? Do both meet the recommended by Harley? I looked my service manual and it states use HD PART# xxxxxxxx, that didn't do me any good.
I went to an Indy to buy some Amsoil Sever Gear and he said to use 75W-90 in the tranny but I see a lot of guys on here use 75W-140. So what's the Pro's and Con's between the 2? Do both meet the recommended by Harley? I looked my service manual and it states use HD PART# xxxxxxxx, that didn't do me any good.
And if anyone ever blasts you for not using the search the way they would like you to, don't sweat it or just blast back. If they would have done a search about blasting people for not using the search feature they would find that most of us don't care and suggest not reading threads if you don't like them.
Road Master
Joined: Feb 2008
Posts: 791
Likes: 36
From: Edmonton, AB
I use Amsoil 75W-90 in mine, and right away noticed quieter 5th gear and smoother shifts. Next time I change out the tranny oil, I'm going with the 75W-140 just to see if it makes much of a difference.
Road Warrior
Joined: Nov 2008
Posts: 1,955
Likes: 7
From: The Great Northwest
Another quick note is that I have also heard a lot of positive comments on Redline Shockproof. I think I'll give that a shot on my next tranny juice swap just so I can compare it to the Amsoil.
Advanced
Joined: Apr 2007
Posts: 82
Likes: 1
From: Idaho Falls, ID
Both of them will give you about the same cold / cool weather performance.
The 75w140 was developed for heavy gear loading and provides greater film strength when hot. Because it is thicker when hot it does provide better cushioning to the gears, which is why some notice that the 5th gear whine is reduced and the shift clunk is less noticeable. The other side is that fuel mileage may suffer a bit, if you worry about every last MPG.
When rebuilding, the only time I have noticed any difference in gear wear is when the gear box is normally loaded heavy and runs hot.
Justin
The 75w140 was developed for heavy gear loading and provides greater film strength when hot. Because it is thicker when hot it does provide better cushioning to the gears, which is why some notice that the 5th gear whine is reduced and the shift clunk is less noticeable. The other side is that fuel mileage may suffer a bit, if you worry about every last MPG.
When rebuilding, the only time I have noticed any difference in gear wear is when the gear box is normally loaded heavy and runs hot.
Justin
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Ultimate HDF Member
Joined: May 2006
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From: Ohio
75-90 is a major improvement over any motor oil. The only thing about 140 is a higher running temp.
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MODERATOR
Joined: Oct 2007
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From: New England
Both will do well and flow the same at cold-start temps but the w140 stuff will take on the properties of a thicker oil at higher temps.
Road Warrior
Joined: Jan 2008
Posts: 1,752
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From: Indianapolis, IN
I use the Amsoil 75W-110. That's a happy median. You get a thicker oil but not too thick.
From what I've been told viscosity numbers for gear oil are not comparable to motor oil numbers. I've been told that 20W-50 motor oil has about the same viscosity of 75W-90 gear oil. So using 75W-90 gear oil is the same as using the 20W-50 motor oil as far as viscosity. I figure using the 75W-110 gives me a little thicker oil but not so thick that it could reduce mpg.
BTW, I do notice a difference in the trans as far as noise when shifting is less and it shifts real smooth.
From what I've been told viscosity numbers for gear oil are not comparable to motor oil numbers. I've been told that 20W-50 motor oil has about the same viscosity of 75W-90 gear oil. So using 75W-90 gear oil is the same as using the 20W-50 motor oil as far as viscosity. I figure using the 75W-110 gives me a little thicker oil but not so thick that it could reduce mpg.
BTW, I do notice a difference in the trans as far as noise when shifting is less and it shifts real smooth.