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.

 

Sonar Chris gets a Gold Star today and an attaboy!
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..

 

Well put. Also, minute amounts of oil does get past the seals. This loss is not always even and there can be an oz difference between the fork legs. When this happens, you get tire cupping - killing your tire prematurely.

 

well said and explained...yes a gold star is deserving

 

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.

 

Sorry...couldn't help myself. I'm booooored. Although it wouldn't surprise me to see a post like that on here.

 

Very Good sonar chris, all oils need to be changed, nothing lasts forever even us.

 

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.

 

Guess all my assumptions were wrong, as sometimes happens. Fork oil change it is when 25K rolls around. Thank you all.