ATF in primary....
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Joined: Apr 2022
Posts: 95
Likes: 164
From: Salem Oregon
As if the link specifically pushing a brand is trustworthy. The claim that atf is to thin to provide protection to chains and gears is laughable. As if transmissions, transfer cases and the like dont have these parts. I do agree it is thinner and if you feather and slip your clutch a lot the lack of its ability to coat can lead to premature clutch problems and/or glazed steels.
Road Captain
Joined: Jun 2014
Posts: 598
Likes: 376
From: Sweden
"We contend that a thicker oil will provide superior metal-to-metal wear protection. Chains and sprockets will last longer using a fluid with an appropriate viscosity.
Below are the kinematic viscosity numbers for AMSOIL Signature Series Multi-Vehicle Synthetic ATF, AMSOIL V-Twin Synthetic 20W-50 and AMSOIL V-Twin Synthetic Primary Fluid. The viscosity is measured at 100°C.
Compared to 20W-50 motorcycle oil and the dedicated primary fluid, ATF is very thin.
For reference purposes, ATF has a similar viscosity to 5W-20 motor oil."
If one forget about Amsoil brand and just consider the tecnical parts, then the above sounds plausible at least to my ears.
But You most likley have a much better knowledge compared to me, so I would never imply that the above is the only truth.
(It's always good to read the comments from someone with a vast experience and knowledge).
* Centistoke (cSt) is used to report the kinematic viscosity of motor oil at high temperatures.
The number reflects the time required for a fixed amount of fluid to flow through a certain sized orifice on the testing device.
Below are the kinematic viscosity numbers for AMSOIL Signature Series Multi-Vehicle Synthetic ATF, AMSOIL V-Twin Synthetic 20W-50 and AMSOIL V-Twin Synthetic Primary Fluid. The viscosity is measured at 100°C.
- ATF- 7.5 cST
- 20W-50- 18.5 cST
- Primary Fluid- 18.7 cST
Compared to 20W-50 motorcycle oil and the dedicated primary fluid, ATF is very thin.
For reference purposes, ATF has a similar viscosity to 5W-20 motor oil."
If one forget about Amsoil brand and just consider the tecnical parts, then the above sounds plausible at least to my ears.
But You most likley have a much better knowledge compared to me, so I would never imply that the above is the only truth.
(It's always good to read the comments from someone with a vast experience and knowledge).
* Centistoke (cSt) is used to report the kinematic viscosity of motor oil at high temperatures.
The number reflects the time required for a fixed amount of fluid to flow through a certain sized orifice on the testing device.
Last edited by K. Lindberg; May 5, 2022 at 12:38 PM.
Seasoned HDF Member
Joined: Aug 2009
Posts: 9,243
Likes: 3,267
From: west Michigan
Well, what I dont recommend is Syn3 in the primary. Maybe its because I had Se255 cans in my heavy *** TriGlide, fully loaded with luggage , and riding 2up
but the clutch slipped & chattered. Even after draining the primary and changing back to F+
the clutch plates were burnished
I wonder if the clutch in your Tri Glide was designed for that kind of a load. Does the owner's manual recommend Formula+ for your Tri Glide's primary?
Road Warrior
Joined: May 2017
Posts: 1,347
Likes: 2,061
From: Phoenix
"We contend that a thicker oil will provide superior metal-to-metal wear protection. Chains and sprockets will last longer using a fluid with an appropriate viscosity.
Below are the kinematic viscosity numbers for AMSOIL Signature Series Multi-Vehicle Synthetic ATF, AMSOIL V-Twin Synthetic 20W-50 and AMSOIL V-Twin Synthetic Primary Fluid. The viscosity is measured at 100°C.
Compared to 20W-50 motorcycle oil and the dedicated primary fluid, ATF is very thin.
For reference purposes, ATF has a similar viscosity to 5W-20 motor oil."
If one forget about Amsoil brand and just consider the tecnical parts, then the above sounds plausible at least to my ears.
But You most likley have a much better knowledge compared to me, so I would never imply that the above is the only truth.
(It's always good to read the comments from someone with a vast experience and knowledge).
* Centistoke (cSt) is used to report the kinematic viscosity of motor oil at high temperatures.
The number reflects the time required for a fixed amount of fluid to flow through a certain sized orifice on the testing device.
Below are the kinematic viscosity numbers for AMSOIL Signature Series Multi-Vehicle Synthetic ATF, AMSOIL V-Twin Synthetic 20W-50 and AMSOIL V-Twin Synthetic Primary Fluid. The viscosity is measured at 100°C.
- ATF- 7.5 cST
- 20W-50- 18.5 cST
- Primary Fluid- 18.7 cST
Compared to 20W-50 motorcycle oil and the dedicated primary fluid, ATF is very thin.
For reference purposes, ATF has a similar viscosity to 5W-20 motor oil."
If one forget about Amsoil brand and just consider the tecnical parts, then the above sounds plausible at least to my ears.
But You most likley have a much better knowledge compared to me, so I would never imply that the above is the only truth.
(It's always good to read the comments from someone with a vast experience and knowledge).
* Centistoke (cSt) is used to report the kinematic viscosity of motor oil at high temperatures.
The number reflects the time required for a fixed amount of fluid to flow through a certain sized orifice on the testing device.
But I also just run Rotella T4 15/40, it's rated JASO MA2 for wet clutches and you can buy a gallon of it for $15 at Walmart.
6th Gear
Joined: Oct 2018
Posts: 11
Likes: 6
From: Ontario, Canada
Ran Rotella 15/40 for years in my Asian bike and now in the primary of my 2014 Sportster, no issues. Rotella is very common among the offshore bike crowd, JASO rated and affordable.
Stellar HDF Member
Joined: Jan 2007
Posts: 2,627
Likes: 1,348
From:
Rotella is good oil. My metric bikes, which utilize a common reservoir for engine and transmission seem to like it just fine even with more horsepower, more torque, more revs and doing triple duty all at once, engine, transmission and clutch.
The H-D primary is fairly rudimentary assembly. The H-D recommended fluids (Formula+ and Syn3) are probably just fine - especially the former. While I did not and will not use Syn3, I have used Formula+ and, like i said, it's just fine. However, I do seem to have better clutch feel - release and grab with ATF Type F so I stick with that and get a free beer or two with every quart in so far as cost versus H-D brand oil.
For me, it probably don't make that much never mind which oil is used in the H-D primary case. I like the grab and the release that Type F provides as well as the free beer.
The H-D primary is fairly rudimentary assembly. The H-D recommended fluids (Formula+ and Syn3) are probably just fine - especially the former. While I did not and will not use Syn3, I have used Formula+ and, like i said, it's just fine. However, I do seem to have better clutch feel - release and grab with ATF Type F so I stick with that and get a free beer or two with every quart in so far as cost versus H-D brand oil.
For me, it probably don't make that much never mind which oil is used in the H-D primary case. I like the grab and the release that Type F provides as well as the free beer.
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