Fork Fluid
Seasoned HDF Member
Joined: May 2017
Posts: 5,915
Likes: 5,928
From: NorCal
There are certainly less expensive one's. I use Bel Ray personally.
Stellar HDF Member
Joined: Apr 2016
Posts: 3,301
Likes: 2,091
From: Masshole
Trending Topics
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,120
Likes: 11,165
From: San Diego, CA
If you are satisfied with your front end performance, stick with the same weight fork oil. If you want to change performance, you can change weights, or even mix weights, to get a performance you like. Just remember, the thicker the oil, the less compliant (stiff) and thinner the oil the more compliant (bouncy) your front end will perform.
Another thing to note, fork oils get thinner, when they heat up. Most have a basic spec and then a 100°C spec. Harley Type E is 20W, but drops to 7.95W @ 100°C. If you are a hard rider, who frequently "works" his suspension hard, you may want to start with a heavier weight fork oil..
I believe most HD bikes come OEM with their Type E fork oil (20W).
If you want a more compliant (bouncy) front end you could go with HD Type B fork oil (10W)...
If you are a canyon carver and want a stiffer front end (Ha, I said stiffer front end) you could go with the Screamin' Eagle Type heavy fork oil. It is also 20W, but fades (gets thinner) less at high temp than Type E.
HD also used to make a very heavy SE fork end oil called extra heavy, which is like 60W... I would guess for racing only, probably unsuitable for street use...
I use Bel-Ray High Performance Fork oil... They make it in 5W, 7W, 10W, 15W, 20W, and 30W. So you can pick a weight and give it try, or there are numerous weights for mixing...
The beauty of fork oil is that it's not that hard to change, and if you pick a weight that doesn't suit you, it's not too hard to change it to something more/less compliant....
Good luck with your decision...
PS- Here's a chart by Spectro Oil on fork oils. It shows the "thinning" of the oil at temp..
Another thing to note, fork oils get thinner, when they heat up. Most have a basic spec and then a 100°C spec. Harley Type E is 20W, but drops to 7.95W @ 100°C. If you are a hard rider, who frequently "works" his suspension hard, you may want to start with a heavier weight fork oil..
I believe most HD bikes come OEM with their Type E fork oil (20W).
If you want a more compliant (bouncy) front end you could go with HD Type B fork oil (10W)...
If you are a canyon carver and want a stiffer front end (Ha, I said stiffer front end) you could go with the Screamin' Eagle Type heavy fork oil. It is also 20W, but fades (gets thinner) less at high temp than Type E.
HD also used to make a very heavy SE fork end oil called extra heavy, which is like 60W... I would guess for racing only, probably unsuitable for street use...
I use Bel-Ray High Performance Fork oil... They make it in 5W, 7W, 10W, 15W, 20W, and 30W. So you can pick a weight and give it try, or there are numerous weights for mixing...
The beauty of fork oil is that it's not that hard to change, and if you pick a weight that doesn't suit you, it's not too hard to change it to something more/less compliant....
Good luck with your decision...
PS- Here's a chart by Spectro Oil on fork oils. It shows the "thinning" of the oil at temp..
Last edited by hattitude; May 26, 2022 at 09:12 AM.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
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
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
Road Warrior
Joined: Sep 2021
Posts: 1,976
Likes: 1,426
From: Black Hills of SD
Even 20wt is considered fairly heavy oil when discussing fork oils. I tend to use 10w to 15w or a mixture of the two to make a 12.5wt. Your riding style, your loaded body weight [ single or double riders], and types of terrain riding on are the gauges to deciding on the wt oil you want. Trial and error are where most people find what works the best for them.
Also, the oil level is easily used to change a forks/suspension characteristics. Rebound and Damping = weight of oil and level of oil in the forks.
One other note - Different brands of oils have different actual "weights" [ viscosities ] even if they have the same weight printed on the bottle.
Also, the oil level is easily used to change a forks/suspension characteristics. Rebound and Damping = weight of oil and level of oil in the forks.
One other note - Different brands of oils have different actual "weights" [ viscosities ] even if they have the same weight printed on the bottle.
Last edited by MarlinSpike; May 26, 2022 at 09:40 AM.