Harley syn3 reformulated 15-50W
Thread Starter
|
Tourer
Joined: Mar 2016
Posts: 282
Likes: 70
From: So Cal
Harley syn3 reformulated 15-50W
I don't know why Harley reformulated the Sync3 20-50 to 15-50 but I used the 15-50 on my last engine change. I have been noticing more engine noise sort of sounds like top end clinging sound that typical occurs during acceleration. This might be indicative of a problem of some sort but I changed the oil but switched to Mobile 1 V Twin 20-50. This noise is almost completely gone.
Anyone else experience this? Another thing is at cold start the bike revved high sometimes to 2400 and with the 20-50 it was pretty normal. I have to do more rides to see how consistent this is.
Anyone else experience this? Another thing is at cold start the bike revved high sometimes to 2400 and with the 20-50 it was pretty normal. I have to do more rides to see how consistent this is.
Popular Reply
Jun 2, 2026, 05:25 PM
Club Member
Joined: Jul 2018
Posts: 604
Likes: 319
From: Wisconsin
Well Felix, as you well know we have thousands and thousands of highly trained Oil Chemists and Liquid Engineers within the walls of this HD site , you are about to get a ton of very molecular oil based dissertations of what is actually happening inside of your Suck, bang, blow petroleum engine, so just wait for all your Oil Based answers to come pouring in ! Hang On...🍿
Club Member
Joined: Jul 2018
Posts: 604
Likes: 319
From: Wisconsin
Well Felix, as you well know we have thousands and thousands of highly trained Oil Chemists and Liquid Engineers within the walls of this HD site , you are about to get a ton of very molecular oil based dissertations of what is actually happening inside of your Suck, bang, blow petroleum engine, so just wait for all your Oil Based answers to come pouring in ! Hang On...🍿
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,548
Likes: 3,747
From: backwoods
Is this limited to softails?
Indian is using something similar. I put 15 in FLH last year
Did not notice difference. I am far from a oil guy.. but read recently the first number is for when cold.
So it is the same for both of them when hot
Indian is using something similar. I put 15 in FLH last year
Did not notice difference. I am far from a oil guy.. but read recently the first number is for when cold.
So it is the same for both of them when hot
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,195
Likes: 11,310
From: San Diego, CA
I don't know why Harley reformulated the Sync3 20-50 to 15-50 but I used the 15-50 on my last engine change. I have been noticing more engine noise sort of sounds like top end clinging sound that typical occurs during acceleration. This might be indicative of a problem of some sort but I changed the oil but switched to Mobile 1 V Twin 20-50. This noise is almost completely gone.
Anyone else experience this? Another thing is at cold start the bike revved high sometimes to 2400 and with the 20-50 it was pretty normal. I have to do more rides to see how consistent this is.
Anyone else experience this? Another thing is at cold start the bike revved high sometimes to 2400 and with the 20-50 it was pretty normal. I have to do more rides to see how consistent this is.
Interesting observations.
In the words of Yogi Berra, "it's like deja vu all over again"...
Prior to selling their Syn3 synthetic oil, Harley used to warn against using synthetic oils in their bikes.
Then in 2003, when the Harley Syn3 20W50 synthetic oil hit the shelves, Harley not only recommended using it, they recommended using it in ALL THREE HOLES....
So, on June 2, 2003, I had San Diego HD perform the 1000 mile service on my 1 month old 2003 Heritage @ 1,115 miles. And for you curious people, I was charged $280.27 for that service.
Based on their recommendation, I had them put Syn3 20W50 synthetic oil in all three holes.
I had approximately 50 miles on the bike after that service, before I pulled in the garage, and drained all three holes. I refilled them with my prior oil choices, before being recommended the Harley SYN3 synthetic oil.
The transmission sounded like a box of marbles, and the the engine sounded as if the valves loosened up...
If there was extra noise from the primary, I couldn't hear it above the engine & trans noise.
I have not even remotely considered buying a Harley oil product (except for their Formula +, which I used for many years in the primaries of my bikes) since then.
When Mobil 1 came out with their Mobil 1 V-Twin 20W50 synthetic oil a short time later (I'm guessing 2004), that has been my "go to" air cooled engine oil since that time.
Last edited by hattitude; Jun 2, 2026 at 07:25 PM.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,195
Likes: 11,310
From: San Diego, CA
Trending Topics
Cruiser
Joined: Oct 2025
Posts: 176
Likes: 71
From: US
Not sure why the oil changed but I quit shorting my oil level by half a quart and the bike is actually quieter and runs better
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
6 Weirdest Harley-Davidsons Ever Sold to the Public
Verdad Gallardo
7 Times Harley-Davidson Chucked Tradition Out the Window
Verdad Gallardo
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,548
Likes: 3,747
From: backwoods
Why do you think this would do anything?