Fork oil

[Du-Rron]

Sup Duey!! Because it's much against my upstanding club etiquette allow me to apologize too for participating in another ..

Back in my early days of MX'n after Yamaha invented the Mono shock and our MX scoots got some very serious suspention, the whoops got deeper and the jumps got farther apart.. During that time period it was not uncommon to swap out fork fluid between heats to refresh the suspention. I discovered by hap err chance (always playing with the scoot) that ATF was actually a very very good alternative to Belray Fork Oil and about 1/4 the price. It got to be a fairly common practice around the tracks.. By the mid 80's Honda was actually specing ATF for some fork applications in the dirt world and their engineers declared ATF as a 10wt Fork Oil..

Something to remember about dirt bike suspention (and other track bikes, like modern day MotoGP sport bikes = R1's-Gixxers and the like, as well as some uppity street bikes) is that the forks are usually equipped with "clickers" that adjust the shims/orvices that restrict the oil flow thru them that create dampening.

On my Gen 1's (and quite possibly on the Gen 2's too) there are no clickers and long ago I played with "dialing in" the forks on my Venture after replacing the OEM springs with Progressives.. Having no clickers to dial them in with and not seeing the advantage to tearing my forks apart to try a reshim/reorvice in forks dampner rods so I could change the fork oils every weekend like I use to do on my MX scoots - I decided to play the Fork Oil weight game and increase/decrease the dampening effect thru oil viscosity (this is another very common practice and why there are multiple Fork Oil viscosities in tiny increments)..

Thru testing, for my ride style, I found 12.5 weight to be perfect when utilized with Progressives and no air added. I have also found that in a pinch, 20 weight Fork Oil used when incorporated with partially sacked out stock Ink Pen springs can slow down the damping enough to keep the forks from bottoming out harshly giving me a chance to get some Progressives installed and keep from ruining the dampeners and having to get into a fork job..

As far as using 5w-20 motor oil? ,,, never tried it.. I personally dont see where using a multi-grade oil would be advantageous when used in a hydraulic fluid application.. If I found myself in the need of Fork Oil and in a bind - I think I would look for a straight viscosity motor oil to use instead but - on the same token,,, I would definitely try the 5w-20 before running em dry!!!!!!

 

Bottom line - in our day and age, Fork Oil is plentiful and highly purposefully engineered.. I would definitely advise to use nothing by Fork Oil for Fork applications.. I know,, I could have said that right at the beginning instead of writing that thesis like I did but I figured I may as well make this a good one as long as you and I are risking getting put on probation anyway

The End

 

Thanks for the insite Puc. Never used anything but ATF before on forks and I was considering using 5W-20 in the RSV when the time comes around.

[Flyinfool]

My view is that fork oil is not that much more expensive to use and is specifically engineered for the job. It is not like you are racing the RSV and changing fork oil a couple of times a day that cost will add up. Fork oil is good for years at a time. if you choose the wrong fluid to put in there you could be putting your life at risk to save $2 a year. is it really worth it. Most venture owners have ended up between 10 and 15W fork oil, I think that putting in 50W will be almost like a solid front suspension. When looking at a multi weight oil like 20W50 ignore the first number. that first number is its weight at -13°F and the top number is its performance at 302°F, I doubt if you will be riding at either temp so why rely on viscosity modifier additives that will break down over time, as opposed to using the right oil to start with.

 

http://www.belray.com/what-exactly-do-multi-visc-designations-mean

[Du-Rron]

My view is that fork oil is not that much more expensive to use and is specifically engineered for the job.

 

http://www.belray.com/what-exactly-do-multi-visc-designations-mean

 

I have seen a lot of stuff used for "Fork Oil" as recommended by the motorcycle manufacturer, from motor oil to real hydraulic fluid and everything in between,

 

 

with a lot of rocket science going into figuring out what "weight" the stuff really is based upon its "Name".

 

ShellTell32.pdfShellTell32.pdf

 

http://www.shell.com/business-customers/marine/marine-lubricants/hydraulic-systems.html

 

 

I've always used ATF with good results. Just wanting to up my game and keep current with what is going on now. I don't normally keep "Fork Oil" on hand so it will be a stretch for me to use the stuff.

Edited November 13, 2017 by Du-Rron

[Flyinfool]

I am just saying that in all applications that require any type of lubricant, I always have used what was recommended by the manufacturer of the equipment and have never been let down yet. There are times where I want to alter the design characteristics of something, and sometimes like in the case of forks, you need to bump up or down a weight. But I stay with the same type of oil. Some engineer spent a lot of time choosing an oil and the hole sizes in the valving to all work together under the conditions of this specific job. yes you might save $5 on the oil IF what you picked works the first time and you do not have to try something else, then you would be in the hole dollar wise. Fork oil is good for many years so that $5 savings works out to less than $1 per year savings. Is it really worth it to be experimenting.

 

Unless of course you are experimenting for the fun of experimenting, then forget everything I just said. Cuz messing around with stuff is also fun, not economical, but still fun. We all know that I am not afraid to mess with things and change the way that it was designed to work and my mods are rarely the cost effective way to.

[MiCarl]

Something also to remember is fork oil doesn't get returned to a reservoir where foam can dissipate. Fork oils will have anti foaming additives.

[cowpuc]

Thanks for the insite Puc. Never used anything but ATF before on forks and I was considering using 5W-20 in the RSV when the time comes around.

 

Right back at cha, you are more than welcome Duey and thank you for moving this over to the Water before either of us became guilty of stealing each others song with our easy form of !! Turned into a very informative thread IMHO!!!

 

[Du-Rron]

Since it is raining and I have nothing better to do...

 

Fork Oil:

 

Motorcycle manufacturers fill their forks at the factory with something slippery. In the old days, the manufacturers used to recommend other name brand oils, Automatic Transmission Fluid, and name brand Hydraulic fluid to refill the forks. After doing a little research, I found that nowadays Manufacturers recommend refilling the forks with their OWN Name Brand labeled oil. I believe that they recommend using their own labeled name brand oil due to marketing and $$$ and it has nothing to do with their own labeled name brand oil being any better for the forks than say... pancake syrup.

 

Fork Oil comes in "Weights" but those "Weights" from brand to brand are not similar. The only way to compare them is to look at their Viscosity as reported by the manufacturer. When a hydraulic fluid is specified by the manufacturer, things become a little easier to compare.

 

I found Bel-Ray is $11.00 for 16 ounces and is mostly light white mineral oil.

bel-ray high performance fork oil 5w item 99300 us_english.pdf

 

Castrol Fork Oil is also light white mineral oil .

CasrolForkOil11067776.pdf

CastrolForkOilBPXE-98RJMS.pdf

 

I found I can obtain light white mineral oil in "hydraulic fluid" specification for $30.00 for five gallons @ Wal-Mart. That comes out to $0.75 for 16 ounces.

 

 

 

 

 

On the other hand... Using what I have been using... ATF, specifically Mercon 5, which is a synthetic oil with antifoaming properties, and will really last a long time in Auto transmissions, so should last a long time in forks too (it does) from Wal-mart for $5.30 for 32 ounces.

 

 

 

 

 

For a lighter weight I could use Dexron VI for $8.50 for 32 ounces.

 

dexronvi.pdf

 

 

 

 

Or for experimental purposes use Racing fluid for $14.00 for 32 ounces

 

 

 

 

 

In any event I don't thinks forks have changed much in the past 40 or 50 years and I think their oil requirements are minimal at best. Before I did some research I was tempted to use 5W-20 motor oil in my RSV forks when the time came. However, now after some research I think I will be using Shell "Rotella" ME 32 as the Rotella line is synthetic, is sold at my local Tractor Supply, and I already have some in the shop.

[Kretz]

Not sure the "Rotella Line" is all synthetic.

AFAIK T4 is dino oil. T5 is semi-synthetic, T6 is full synthetic. But that may not be what you're talking about as you are talking about fork oils.

[cowpuc]

Since it is raining and I have nothing better to do...

 

Fork Oil:

 

Motorcycle manufacturers fill their forks at the factory with something slippery.

 

Indeed,,, and WOWZY was it strange smellin stuff.. I always thought the factory fork oil in those real early Yamaha DT's smelled like some kind of fish oil - man did it stink!! If I'm liein I'm diein - I honestly think the Japs were compressing whale fat or fish hides to get the oil out of em to use in forks or something.. Was also the day and age when a gangster ripping around on one of those DT's could stop at the Yam shop and buy "Oilzum" 2 stroke oil from them right out of the 55 gallon drum and Klotz bean oil was the sweetest smelling stuff EVER if you were running pre mix!!!

Be interested to know what you think of the Rotella when ya swap er out Duey!!!

[Du-Rron]

Not sure the "Rotella Line" is all synthetic.

 

Shoulda said the Rotella S4 ME series.

[Du-Rron]

Indeed,,, and WOWZY was it strange smellin stuff.. I always thought the factory fork oil in those real early Yamaha DT's smelled like some kind of fish oil - man did it stink!! If I'm liein I'm diein - I honestly think the Japs were compressing whale fat or fish hides to get the oil out of em to use in forks or something.. Was also the day and age when a gangster ripping around on one of those DT's could stop at the Yam shop and buy "Oilzum" 2 stroke oil from them right out of the 55 gallon drum and Klotz bean oil was the sweetest smelling stuff EVER if you were running pre mix!!!

Be interested to know what you think of the Rotella when ya swap er out Duey!!!

 

The Toyota Rear Ends of the 70's - 80's must have been filled with the same stuff. Smelled astringently nasty (much worse than moly). Could not wash it off your hands. Kinda smelled like... poop.

 

Never smelled Klotz that I can remember. My favorite now is Marvel Mystery Oil. Smells kinda like bubble gum.

 

Will let you know on the fork oil change out.