Transmission fluid looks like Pepto Bismol
Grand HDF Member
Joined: Mar 2011
Posts: 4,816
Likes: 1,320
From: Good roads, cold beer
Im new to Harley's, just got my first RG last week. Since I bought it used Im going to do a complete oil change for all 3 holes but it looks like Harley recommends using regular or full synthetic oil for the transmission as well? Is that correct? Just doesn't sound right to me, I've never heard of using anything but transmission fluid in a transmission on any vehicle. I've heard about this red line trans fluid a lot and think Im going to go that route over the same oil that goes in the engine. Any suggestions?
many run a gear lube in the tranny (Mobil synth etc)....HD uses Syn3 in all 3 holes.
Some of us run Formula+ in the tranny (and primary), which I do now. Do a forum search, many threads to read on it. Good luck.
Tourer
Joined: Jun 2018
Posts: 437
Likes: 107
From: Indiana
Sorry, its a 2012 RG Ultra. Thanks for the info.
Seasoned HDF Member
Joined: Aug 2009
Posts: 9,239
Likes: 3,261
From: west Michigan
Im new to Harley's, just got my first RG last week. Since I bought it used Im going to do a complete oil change for all 3 holes but it looks like Harley recommends using regular or full synthetic oil for the transmission as well? Is that correct? Just doesn't sound right to me, I've never heard of using anything but transmission fluid in a transmission on any vehicle. I've heard about this red line trans fluid a lot and think Im going to go that route over the same oil that goes in the engine. Any suggestions?
If you want something heavier than Syn3, in the Trans, use Harley's Formula +.
Seasoned HDF Member
Joined: Apr 2008
Posts: 23,399
Likes: 8,509
From: Spartan Country, Michigan
RK4ME.... I pretty much agree with you with the exception of synthetic in the primary.... I installed an Energy One clutch in my Sportster and they recommended I not use HD Syn 3..... that has some added "slippery" stuff that could create clutch slippage issues. They recommended type f ATF.... I used that and never had an issue. I have since gone back to Formula + in the primary and a gear lube for the trans, and AMSoil for engine. My ONLY concern over oils is this: if you use a synthetic motor oil in the primary, be aware you MAY have some clutch slippage. There will be some of you who will tell me I'm full of it, I've never had issues, but when a clutch manufacturer tells me (and he was very hesitant, I had to push to get the reason) that some oils have additives which are not good for clutches. ATF if you think about it, is used in automatic transmissions, sure, but remember there are clutches, gears, and bearings in those as well!!!
Regardless, I feel if you use a good brand oil, you should be just fine.
Regardless, I feel if you use a good brand oil, you should be just fine.
Road Master
Joined: Sep 2016
Posts: 1,048
Likes: 492
From: Heart of Georgia
Im new to Harley's, just got my first RG last week. Since I bought it used Im going to do a complete oil change for all 3 holes but it looks like Harley recommends using regular or full synthetic oil for the transmission as well? Is that correct? Just doesn't sound right to me, I've never heard of using anything but transmission fluid in a transmission on any vehicle. I've heard about this red line trans fluid a lot and think Im going to go that route over the same oil that goes in the engine. Any suggestions?
Outstanding HDF Member
Joined: Dec 2012
Posts: 2,699
Likes: 520
From: Palm Coast, Florida
Don't tell anyone, but all I've ever run in my crankcase and primary is Rotella 15W40 diesel oil, and Redline Shockproof in the tranny.
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Seasoned HDF Member
Joined: Aug 2009
Posts: 9,239
Likes: 3,261
From: west Michigan
RK4ME.... I pretty much agree with you with the exception of synthetic in the primary.... I installed an Energy One clutch in my Sportster and they recommended I not use HD Syn 3..... that has some added "slippery" stuff that could create clutch slippage issues. They recommended type f ATF.... I used that and never had an issue. I have since gone back to Formula + in the primary and a gear lube for the trans, and AMSoil for engine. My ONLY concern over oils is this: if you use a synthetic motor oil in the primary, be aware you MAY have some clutch slippage. There will be some of you who will tell me I'm full of it, I've never had issues, but when a clutch manufacturer tells me (and he was very hesitant, I had to push to get the reason) that some oils have additives which are not good for clutches. ATF if you think about it, is used in automatic transmissions, sure, but remember there are clutches, gears, and bearings in those as well!!!
Regardless, I feel if you use a good brand oil, you should be just fine.
Regardless, I feel if you use a good brand oil, you should be just fine.
Last edited by RK4ME; Jul 3, 2018 at 12:26 AM.
Road Master
Joined: Jul 2015
Posts: 959
Likes: 267
From: San Fernando Valley, CA
Your aftermarket clutch probably uses a different material on the friction discs that Harley uses on theirs. I ran Syn3 in my Road King's primary for 50K miles and never had a problem, even with full throttle powershifting in side-by-side acceleration comparisons with other bikes. Think of all the unit construction bikes that run synthetic oil for the engine, clutch, and transmission. Last time I checked, Mobil recommended their 10w-40T synthetic oil for use in Harley primaries.