What type of fork oil?

qman

Joined
Feb 7, 2015
Messages
64
Location
Colorado Springs, CO
Bike
1992 ST1100
I've searched the threads and found a ton of threads on fork oil weights. Didn't find anything on this question. What type/brand of oil do you use in our forks?

My shop manual (Honda) says "use Honda fork oil xxxxxx".

Can't I use any ole fork oil? My 83 Honda Magna calls for ATF. What about using that? Just wondering what y'all use.
 
I filled with Silkolene 10w Racing. The better the oil, the better the ride, I hear. My 1100 has produced since, for an old machine, a much better, smoother ride. Even with stock springs!



Styles
 
Forks do not subject the oil to the same heat, moisture, acids and combustion by-products that your engine oil is exposed to. What is important is a measured viscocity, a clean oil with no contaminants that is stable and will not break down with exposure to air, and is not hydroscopic (like brake fluid). The brand is not very important.
 
I used Bel-Ray in my ST1300. I used Bel-Ray when I used to race flattrack. Proven winner. Previous posters are correct, in that the brand isn't as important as with engine oil. On the other hand, you want to use a company that has been race proven for a long time, to make sure viscosity is accurate.
:tb1:
 
SMSW said:
Forks do not subject the oil to the same heat, moisture, acids and combustion by-products that your engine oil is exposed to.
Click to expand...
Well, you guys must have very smooth road surfaces over there... ;-)
Our frost beaten, patch-worked mountain roads are quite challenging for suspensions and damping oils... like hours of rattling over old cobblestone-pavement...
On such runs my fork bottoms can get hot beyond touch...
Then there contaminations due traces of dust and road-spray... fork oils have to take a lot...

mean13 said:
I used Bel-Ray in my ST1300.
Click to expand...
I'm also sold to their products...
But each MFG has different viscosities... a 7W fork oil from brand A might equal a 10W from brand B, etc... (there was an informative thread somewhere on this forum)
Fact is that synthetics are superior due being more tolerant to humidity and other impurities.
 
qman said:
I've searched the threads and found a ton of threads on fork oil weights. Didn't find anything on this question. What type/brand of oil do you use in our forks?

My shop manual (Honda) says "use Honda fork oil xxxxxx".

Can't I use any ole fork oil? My 83 Honda Magna calls for ATF. What about using that? Just wondering what y'all use.
Click to expand...
For your ST1100, Honda SS-8 (stock, it is 10w) or BelRay 10w.
 
For the last 140K/17yrs I've used Pro Honda SS-8 (10wt) Suspension Fluid with Progressive Suspension springs. Regular fluid changes. I'm not a 'Ricky Racer.' :)

FWIW YMMV

John
via iPhone 4S
 
I only have my st1100 since Febuary this year. 1994 47k on the clock. Very carful owner before me. I'm starting to notice the front forks are starting to dive a bit more under braking than they used to. Is it time to change the seals & oil or just the oil. No leaks. I have no record as to when they were last done. Best bike ever,........


Sent from my iPad using Tapatalk
 
I'm starting to notice the front forks are starting to dive a bit more under braking than they used to. Is it time to change the seals & oil or just the oil.
Click to expand...

Wouldn't hurt to R&R suspension fluid. When you have the forks off, remove the anti-dive unit and check that the sealing lip of piston isn't compromised. BTDT The degradation over time can sneak up on you. I am now recommending this for all older and/or high mileage ST1100s. FWIW YMMV

John
via iPhone 4S
 
Many opinions out there when you ask this question. I rebuilt my 97ST forks in the winter of 2013 and used synthetic ATF. I'm not a canyon carver so not concerned with ultimate performance. Prior year Honda motorcycles spec'd out ATF for forks and that makes sense if you think about it. No problems during last years summer riding and they still ride great so far this spring. Use a good fork oil or ATF, you'll be okay.
 
qman said:
I've searched the threads and found a ton of threads on fork oil weights. Didn't find anything on this question. What type/brand of oil do you use in our forks?

My shop manual (Honda) says "use Honda fork oil xxxxxx".

Can't I use any ole fork oil? My 83 Honda Magna calls for ATF. What about using that? Just wondering what y'all use.
Click to expand...

ATF is 'old school' and does NOT provide correct dampening properties. If you intend for a decent riding/handling bike, use a good quality fork oil such as Bel-Ray or Silcoline. Dampening orfices being slightly enlarged from oil friction over time, I suggest increasing that to a 10w fork oil;).
 
We're talking about 17-20 year old machines here after all. I'm an "old school" kinda guy anyway.:D AFT weighs in at about 7-8 weight. A 10wt oil would be slightly heavier damping I guess. Riding within my capabilities, I'll probably not be able to tell the difference. Modern synthetic fluids have come a long way in 20 years. Through last summers riding season the ST ran great and rode well.
 
Qman. You need to get either a Honda Service manual or something like a Clymers manual. Questions like this are answered in the books.

My Clymers book says SS7 which is the equivalent of 5w. I use Bel-Ray in all of my bikes even my vintage stuff. I have never used AFT and I have read threads that say that the AFT is not compatible and the seals will fail sooner. I have no proof of this.

Our ST1100 have a generalized dampening system meaning that they work okay across all road surfaces. Depending on the ride you are after the oil weight may impact the low speed ride or the high speed ride. The orifices in the dampening rods are designed for the fork oil weight recommended by Honda. In my opinion I highly doubt that the orifices sizes will enlarge based on oil flow alone. Although I have not checked this the logic does not make sense unless one has hundreds of thousands of miles on the bike. There needs to be some other abrasive in the oil to make this happen.

Two things will affect your dampening, oil weight and air volume in the fork cavity. Oil is not compressible the more oil the less dampening. Springs do not impact dampening. I believe Bel-Rey come in like 5, 7, 10, 12, 15, 20, etc.

I run Bel-Rey 5w oil and have 1 KG straight rate Racetech springs. I did try 10w with these springs and found the dampening to be very rough at highway speeds. Back to 5w.

If you are interested in suspension get the Racetech Suspension Bible.

Here is an interesting article. http://racetech.com/html_files/DampingRodForks.HTML
 
Last edited:
I recently replaced my fork seals and now use something new to me. I have always had good luck with Bel-Ray fork oil. Experimented with mixing wt's different wt's etc. I am now using 10 wt Synthetic Amsoil fork oil and believe me, it is the best I have used. Using the cheap ATF is not recommended.
 
Do not use ATF use fork oil go buy some BelRay fork oil in the weight you want. It is not cheap either. $12 to 15 a bottle, should be enough for both forks.
 
Grabcon said:
Do not use ATF use fork oil go buy some BelRay fork oil in the weight you want. It is not cheap either. $12 to 15 a bottle, should be enough for both forks.
Click to expand...

Uhhhh.......gonna need two bottles, as one is just not quite enough to specs.........marketing ploy again.
+1 not using ATF. Not sure where others are reading it from...but sure isn't any factory manaul;).
ATF does NOT have the dampening properties of designated FORK OIL........and yes, with 30+ years in the moto-x world under my belt, aside from the 50+yrs. overall in the cycle world has some credibility;). Back in the mid 70's, us 'poor boys' used ATF, but we also knew dampening and aireation was gonna be an issue, specially the hotter the forks got from OIL friction thru damening orfices. It's your bike, do as you wish though:).
 
Brant said:
Uhhhh.......gonna need two bottles, as one is just not quite enough to specs.........marketing ploy again
Click to expand...

Depending on year a one liter bottle may or may not be enough. Check the manual for your specific year.
 
You must log in or register to reply here.
Top Bottom