I have an 07 Road King. Manual has fork oil change at 50,000. Other things I've read states 20,000 mi. ?

 

You won't believe how dirty it gets in 20K mi. I'll go to a heaver oil when I get the chrome front end on this winter.

 

I did a write-up here on an easy way to change the oil in '06 and later forks. It is a one-hour job and I'm going to schedule changes every 20k regardless of the manual's spec of 50k.

Earlier bikes have change intervals much shorter, and my '96 was 12k. I did it every 10k on that bike because with the air forks it was a simple 20-min. job using the vacuum method outlined in the manual. I don't know how you would change oil in cartridge forks ('02-'05) other than complete disassembly as per the manual.

 

I changed mine at 52k and I will change it again after about 20k maybe sooner. I put the SE heavy in and like it alot better. Wished I had changed it sooner. iclicks write up is great and can help you alot.

 

I've noticed the guys that were kind enough to respond have bikes with fairings. I keep my windshield on most of the year, but the weight difference between the fairing and shield has to relate to a stress difference on the forks and oil?

 

Sounds logical to me but I don't know.

 

I don't think the diff is that great, if you want to stiffen up the front then use the SE Heavy and you won't dive when stopping, etc. I would change it when you feel the front is getting like it's soft. You can change it by draining and putting in a little at a time then pumping you forks til you get all the oil in.

 

That is a great write-up iclick. I think I can even do it by following your instructions.

 

FWIW, I have an 06 SG and weigh 230. I tried the SE heavy oil and while it stopped the diving the forks felt harsh. I went to a 50/50 mix of heavy and standard oil and raised the level by 1oz. Minimal diving under braking, good feel and the forks don't bottom on hard hits. Some guys will claim you blow seals but with the little bit I added it just takes away enough air space that the remaining air pressures up just enough to cushion the hard hits.

 

I just did the 10k service on my ultra and had them do the heavy duty oil change on the forks to get the stock crap out of there. What a difference! No more nose dive under braking and the bike feels firm, but not stiff on the road. I'll change it now every 15 - 20k miles depending on how the front end is feeling.