Why change fork oil, ever?
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Road Master
Joined: Jul 2008
Posts: 811
Likes: 53
From: Emmett, Idaho
Why change fork oil, ever?
This seems senseless to me. Fork oil never gets heated, is never exposed to combustion, can never break down from any environmental or operating conditions that I can conceive. Has anyone given this some thought?
You are very wrong in your assumptions. Fork oil gets hot as hell. It gets pushed through a bunch of small holes and valves to provide dampening, the friciton of the oil moving makes it quite hot. If you take a ride for 20 miles or so, and then drain the oil, you will burn yourself with it. This heat will break down the oil and cause a viscosity change, making your bikes forks work less efficiently for suspension and braking. Fork seals are good, but they do break down and allow water to get in, thus contaminating the oil. You are only supposed to change the fork oil every 25K as it isnt subjected to the same heat as motor oil, but it will break down after mileage.
Elite HDF Member
Joined: Jun 2008
Posts: 4,151
Likes: 0
You are very wrong in your assumptions. Fork oil gets hot as hell. It gets pushed through a bunch of small holes and valves to provide dampening, the friciton of the oil moving makes it quite hot. If you take a ride for 20 miles or so, and then drain the oil, you will burn yourself with it. This heat will break down the oil and cause a viscosity change, making your bikes forks work less efficiently for suspension and braking. Fork seals are good, but they do break down and allow water to get in, thus contaminating the oil. You are only supposed to change the fork oil every 25K as it isnt subjected to the same heat as motor oil, but it will break down after mileage.
You would be amazed at the number of people who perform there own service and never change there fork oil.. And the number of dealers who ignore it as well..
Road Captain
Joined: Dec 2007
Posts: 614
Likes: 3
From: Northern Ontario, Canada
You are very wrong in your assumptions. Fork oil gets hot as hell. It gets pushed through a bunch of small holes and valves to provide dampening, the friciton of the oil moving makes it quite hot. If you take a ride for 20 miles or so, and then drain the oil, you will burn yourself with it. This heat will break down the oil and cause a viscosity change, making your bikes forks work less efficiently for suspension and braking. Fork seals are good, but they do break down and allow water to get in, thus contaminating the oil. You are only supposed to change the fork oil every 25K as it isnt subjected to the same heat as motor oil, but it will break down after mileage.
Ultimate HDF Member
Joined: Nov 2008
Posts: 8,280
Likes: 3
From: Portland Oregon
You are very wrong in your assumptions. Fork oil gets hot as hell. It gets pushed through a bunch of small holes and valves to provide dampening, the friciton of the oil moving makes it quite hot. If you take a ride for 20 miles or so, and then drain the oil, you will burn yourself with it. This heat will break down the oil and cause a viscosity change, making your bikes forks work less efficiently for suspension and braking. Fork seals are good, but they do break down and allow water to get in, thus contaminating the oil. You are only supposed to change the fork oil every 25K as it isnt subjected to the same heat as motor oil, but it will break down after mileage.
Seasoned HDF Member
Joined: Apr 2008
Posts: 23,042
Likes: 12,326
From: Arkansas
This is great...You guys know your stuff!!! Now maybe you can help me. I've been wanting to change my fork oil but can't find the drain plug or the fill plug. I've looked everywhere and I'm starting to think they forgot to put them in when they made my front end.
If it will help you to help me I will tell you that I have an 05 FLSTSC.
If it will help you to help me I will tell you that I have an 05 FLSTSC.
Seasoned HDF Member
Joined: Apr 2008
Posts: 23,042
Likes: 12,326
From: Arkansas
Sorry...couldn't help myself. I'm booooored. Although it wouldn't surprise me to see a post like that on here.
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Road Master
Joined: Nov 2007
Posts: 790
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From: AZ
Bought a 1995 Heritage Softail Nostalgia in 2001. Did not have the time to do a full service so I dropped it off at the HD Dealer. Put some miles on bike and when I needed another full service I found an INDY with good reputation I could trust. The Indy called me with questions on last full service. I returned to his shop, the right fork tube drain bolt was stripped. He removed the bolt with a lot of hard work and pure black oil came out while fresh looking oil came from the left tube.
I called the dealer and was told paperwork did not indicate any issues. I learned that fork oil does wear out and the mechanic at the dealer did not care.
I bought a service manual and take care of what I can. I have complete trust in the Indy. When things get slow for him I drop off the bike and let him go through it.
I called the dealer and was told paperwork did not indicate any issues. I learned that fork oil does wear out and the mechanic at the dealer did not care.
I bought a service manual and take care of what I can. I have complete trust in the Indy. When things get slow for him I drop off the bike and let him go through it.