Old thread but I wanted to post anyway.
I purchased my then new Big Twin Harley new 26+ years ago ( 80 c.i. S&S carb EV27 cam ).
I have performed all my own fluid changes myself an average of 2x a year oil and filter and 1x a year trans and primary. So that's about 50+ oil and filters on the same bike using many brands of oil and filters!
I have some strong opinions of what's the best oil filters and trans / primary fluids that my ear and butt Dino has told me what works best in my bike and what to avoid.
Perhaps my many fluid changes and experiences will help someone.
1st, I learned early what NOT TO USE! Or what I will say "my bike don't like".
the 1st or 2nd year I tried Mobil 1 V-Twin Synthetic 20-50. The bike hated it, I drove about 15 miles and pulled up to a stop sign and tic, tic, tic, out the top end of my engine. I turned around, got it back home, dumped that 30 mile oil and refilled with Dino oil and have NEVER heard a tic again. Now 26 years later she has never had one more drop of Synthetic engine oil ( I have used Synthetic trans fluid ) and I have never heard that tic again!
Early on I used and liked Revtec oil and filters for many years but I cant find it any more. I have used the Harley brand oil from time to time with okay results.
When the bike was 4-5 years old a local small shop suggested I try Synergyn Syngear II ( synthetic gear oil ) in my transmission and WOW my bike LOVED IT! Finding neutral was super easy, less 1 st gear clunk and less metal on drain pug when changing it but after using the Syngear about 15 years, it is no longer made so I was forced to change.
I tried the new Harley Heavy Synthetic in the trans and the trans hated it, Can't find neutral, 1st gear clunk returned, I was never so sad to see a trans fantastic fluid (Synergyn) go away...
While researching an alternative to my long gone Synergyn I ran across Bel-Ray V-Twin mineral engine oil, primary and trans fluids.
The reviews and specs looked great so I changed all 3 fluids to Bel-Ray and I can say after 50+ oil changes and 25+ trans and primary changes I NOTICED I HAD A BETTER RUNNING AND RIDING HARLEY WITH BEL-Ray! My wife riding on the back even noticed the engine was smoother / less top end noise.
Seriously, the engine top end was smoother and has the least amount of noise I have every experienced on this bike.
The trans fluid took me back to the Synergyn days and that surprised me as the Bel-Ray trans fluid is Mineral but the shifting was smoother, I could find neutral again, the bike felt so much better.
So now after the last few fluid changes. Bel-Ray V-Twin Mineral is my new fluids of choice for my old 1997 one owner Harley. My filter of choice is the WIX 30 micron filter made for EVO ( NOT THE 5 MICRON oil filters).
I will also report I added a new Harley to go with my old EVO, A 2023 Harley Street Glide 107 Stage 2 with cam.
I'm old school and like to get break-in oil out quick on everything from a lawn mower to a new Harley so I changed the Factory oil and filter at exactly 100 miles, I used the same Bel-Ray Mineral 20w-50 and once again I noticed the engine top end was quieter on my new bike same as my old EVO! For now I did use a new stock Harley 5 micron oil filter and will stick to that filter until I am comfortable with aftermarket 5 micron spec or my warrantee expires. In the event that I allow the dealer to do the 1k service I noticed he stocks Bel-Ray!
I'm a big fan of mineral oil vs Synthetics is some applications, lawn mowers and air cooled EVO Harleys as example and simply change the oil often. The idea that the mineral is smoother / quieter in my new modern Harley has me thinking, do I continue to run mineral Bel-Ray for the life of my new bike or do I try the Bel-Ray synthetics as the M8 newer Harley engine is a much hotter running engine than my old EVO and I understand synthetics / heat but just not sure of my long term oil plan with my newest bike.
I may just do what I have been doing, Bel-Ray mineral 2x a year? OR I can see myself at least trying the Bel-Ray Synthetics as the reviews are fantastic but my old 97 EVO will never see Synthetic,
Regardless, I can say now on an old bike and a new bike, I noticed a smoother, quieter engine when using Bel-Ray!
So best all round for Harley M8 touring? Will it be Bel-Ray Mineral or Bel-Ray Synthetic? I will know by mid summer !