Yeah, my mechanic told me that I need thicker oil for my fork. I'm trying to lose weight but changing oil is faster.

No hats on backwards, no silly music......this man is to be trusted.

30 belray babe!!! 2005 Softail Harley-Davidson put it in you don't need Progressive Springs the 30 weight,holds it nice and tight around the corners

Straight forward, and, superb simplicity in explanation in your education again... spoken truly. Thank you Mr, D Moss... blessing to you sir.

Did that on my CB500Four K1 40 years ago :-) Got a set of Girling gas shocks for the rear so somthing had to be done with the fork ;-D Used 3 liters of fork oil (3 diff. viscosities), two sets of preload bushings and a month of experimenting - ended up with a "killer-suspension". Gave my confidence a "god-like"-no-corner-is-too-tight-and-breaking-will-be-too-late-boost - But got many 750+cc riders into severe troubles trying to keep up with that little "CB5" ;-D Used one step heavyer oil, a little extra preload and that much extra oil that it just stayed on a 5mm compressed air cushion and didn't bottom out on "solid" oil :o)

Ok Dave, you're still getting views. The service manual for my 2018 Suzuki GSX-R750 calls for SS-47 10W fork oil and my local dealerships only have BelRay 10W fork oil (Viscosity Index 118), so I ordered 2L of the Maxima 10W (Viscosity Index 182) because theoretically the 182 V.I. will have better stability throughout the cool to hot temp range of the day. And...I'm a lighter weight rider at 150lbs with gear that mostly rides in warmer Southern US temps, so I did not opt for a 7.0-7.5W fork oil (yet) future testing TBD. Also, thanks to your BPF vid which I view via my subscription to the Dave Moss Tuning website, I have found BPF fork servicing to be a relatively simple DIY function and will be performing my own fork services myself. All this to say that you have been VERY helpful and I am very glad I paid the $49.95 annual subscription fee for your site. I highly recommend others do so also!

Great stuff Dave - the whole suspension thing is a fascinating subject! 👍🏻🛠

Another simple but helpful video Dave. It is even more helpful when your bike have no fork adjustments whatsoever. Just like my Yamaha XJ6 (FZ6R). As I am just a slightly heavy and riding a bit too aggressive on weekends I opted to go from standard 10W to 15W. So far so goog.

I tried going from 5 to 10 weight...huge difference and was quite harsh. Went back.

Thank you for the life of Brian reference. +2 cool guy points!

totally agree change your oil! when i got my 2002 cb900f hornet it was super comfortable just floated along extent to get used to the move from 2000 wr400f to 2002 cb900f it let me concentrate on looking and pointing the bike where i wanted it to go and also to install trust that the bike can and will sort itself out not if but when its slippery or bumpy being soft got rid of the "pucker" factor that instinct to shit your self when something unexpected happens about 2 weeks ago the seals leaked on one side so i orded the seals bushes and oil pulled them full brake down clean dry fill per book cycle check lvls back in bike the diffrence in the feel and feed back wow huge not sure what oil or how long it was in there for but wow so much more crisp and turnable its like the shock had been changed or re worked who knows but now that im really starting to ride the bike a good bit faster in the bends to load the suspension and lunch out of the bends its just addictive getting the power on as it opens up and the bike digs down pushed out a little and rips out of the bend i really really want to go do some ride days but the cost! here in Brisbane aus its like 300 bucks a day plus gear as i dont have track gear just a summer jacket and gloves yeah i know but gear is cheeper and easyer than skin grafts but dam why do they make it so expensive to go ride in a much safer place than the streets? it should be like 30-50 bucks to go ride maby more people would go rip around the track rather than on the streets doing dumb stuff

thank you so much sir , now I'm putting liqui Moly 15w fork oil in my pulsar ns200. I'm 5.9" 67 kgs, but I'm a aggressive driver so OEM fork oil don't help me..that's the main reason I want to replace my bike fork oil. Again thnq so much sir ... Love from Delhi, India 🙏

I LOVE that you quoted my favorite Monty Python movie, so very underrated lol.

This is gold content now i know i can change the viscosity of my fork damper behaviour.

Had to buy fork oil because of a massive leak out. I went for the "same weight" but with a known brand, for street and off-road, one, i actually go on some light off-road.. What an improvement! So, it might be a good idea to try a good/another oil first, before changing the weight.

You heard it here folks. Change your Forken Oil !!

I like the way this dude talks

well,i did not knew that my actual weight was important in the choice of the fork oil thickness,,its very interesting.185 pounds and 5 feet 8 ,,an old man of 64 with a stock Bandit 400,1991.i am working on a winter project here in Quebec .After the front fork i must found an alternative for my rear suspension,,it is so hard.But i will dismantle and grease ALL the rear pivot ,,bushings,,bearings i will found because i see no grease zott anywhere.Thanks for your Instructive video.Merci .Gervais de Riviere-Bleue au Quebec

The David Attenborough of moto maintenance....more please

Dave thank you very much. Today I managed to change fork oil to my marzocchi rac 50.was very easy but took me almost a day. The cap opened very easy with a pin spanner tool and I managed to drain 625 ml of old oil from total 655ml (according to manual). Not bad I think. I exercised the forks couple of times (6 or 7)thr last 200ml came out really hard. But was very interesting that the forks without oil work like a normal spring.oil makes hudge difference! I used 5w as you suggested to me to some other video, though I didn't ride it yet, cause I need to make some more things, but it works really really smooth and it changed sound, it sounds Ike pressured air. Pretty cool. By the way I changed oil too, to my ohlins steering damper and now it's awesome! Thanks once more for these amazing guides. You re cool Dave!

6k miles? Oh crap! Mine was factory filled 23k miles ago. Race tech compresser and level.gauge STAT.

Really useful video, I'm about to change the fork oil on my old Ducati 851 fitted with Showa GD11 forks, looks like I need to find an equivalent to SS8 Fork Oil

It's the 5wt Racetech ultra slick. Wish I was in CA, sadly I'm stuck in Ohio. Riding the 555 Triple Nickel today though, which is a hoot. Thanks for the reply Dave. I'll try out the 7.5wt and see how it fairs.

With the recommended 5 weight the bike was comfortable but dived too easily when the front brake was pulled on. Going to 7.5 weight makes the ride it a bit harsher on bumps, but has reduced dive substantially, which allows me to ride more aggressively which means fun time.

Actually, that’s a very good analogy, Dave. This is why I like your videos.Practical and a little reasonable info. My dumbass dealer don’t know the difference between 2,5 and 15w oil

I wish I had an app that would have this guy read my email. I can just imagine what that spam from Domino's Pizza would sound like!

Ohlin Fork Oil for Ohlin Cartiges only has a part Number.. I found a spec chart it basically is 5W .. Ohlin Fork Oil $28 per Liter Bel Ray Fork oil $16 per Liter..

Quick question, I put harder density, manual says 10, I'm sure D9, but I've put 15 in, changed oil seals, dust seals!!!, it's kind of leaking, residue on forks... i used red stuff came with seals, put that on inside and out....Is it leaking because of stronger oil!?....if answer is no, then will try and clean them on bike, if failing that!!!... Might be a bad set from eBay (shock - horror) but all did have a tight fit....manual says 441....I put in around 450 each leg, surely this wouldn't be the problem.... let us know if U can, will try tomorrow... I know I have the screw setting on top, I wonder if I loosen...hmmmm 🤔, only 1 way to find out.... ✌ & 💖 🌍 we 🙏

Suspension guru your never too old to learn something new as much as U know stuff someone's know d more like Dave Moss 🏍️

Hey, I am dead because I did not change my oil. I came back to warn everyone. Thank You 🙏. Peace Out. ✌️

Back in the 60s here in the UK there was really only one fork oil Castrolite 30 mineral oil , a straight grade mineral oil that was an upgrade for most forks and sits around Bel Rays 30 Fork Oil as far as viscosity at temps ( Cs ) is concerned .The forks characteristics was then modified by the quantity and compressibility of the remaining air gap . All done with adjusters now . Isn't modern shit wonderful ?

I have passed 100 000kms not long ago on my bike. The front feels softer than it used to, probably it is time to change fork oil

A world famous track training school instructor once recommended us to use thinner fork oil rather than thicker. If I remember correctly; his reasoning was that thinner oil would permit "faster" (and/or finer adjustments) functioning of the valves and suspension mechanism, therefore it'd provide better surface tracking&traction. (Therefore also: viceversa) I would like to hear your view on this subject. Thanks for your diligent work. I have your DMT app. Although I'd prefer a simpler scheme to pay, I am a satisfied subscriber ; )

im a big guy and switched to 20 weight on my 87 concours and it felt way better. previous stock weight it felt was kissing the pavement in front everytime I was braking... lol

Dave's not the Messiah, he's just a very naughty naughty boy. Lol!

Hey Dave what is your preferred brand of fork oil? Or do you stick with manufacturers recommendation on brand for fork oil.?

I've heard that viscosity breakdown is due to heat and that fork oil doesn't experience this breakdown as it's the only oil on your bike that doesn't get hot enough to. Further the only reason why fork oil needs to be changed is because of particulate buildup from the spring compression causing lots of little particles of metal. Meaning as long as you filter your fork oil every 5k miles you can reuse it as there is no viscosity breakdown. It that not true?

Dave, I did just what you mentioned. When changing fork oil on forks I was rebuilding, the manufacturer spec was 10W but when I looked at the viscosity chart as tested I went with a Silcoline Pro RSF 7.5 (I think) to get a 10 W. The bottom line was...after researching the weights as actually tested, the claimed weight on the bottle has almost nothing to do with its actual weight. Was I right?

switching from weak /soft/stock gl1800 fork springs to progressive springs.. Since the new springs are going to rebound faster than the old stock springs..Do I stay with the recommended weight fork oil.. I am pretty sure my 2002 Goldwing has cartridge forks. Is the fork oil used to control/ damp the spring rebound as well as a lube ,Or just as a lubricant? also: i dont think so, BUT- is thicker fork oil more or less likely to blow fork seals?? also: when refilling the fork tubes with fork oil, should I have the tube slightly inserted into the lower fork leg when reinstalling the cap/ top??The point is, so that I can Displace a bit of the air space in the tube,So that I won’t have trapped air pressure in the fork tubes.. I remember when they used to use air in suspensions, which I am pretty sure was the worst type of suspension spring you can use because of the rising rate .. I remember motocross bikes had a Schrader valve at the tops of the fork tubes in the 90s, that was to let air pressure out of the fork tubes that built up while riding in the tubes.. Does this make sense to push the fork tube in slightly to account for sag to displace some air space before installing the cap?

as an inverted fork bike owner, the labor for changing fork oil isnt cheap either if you are hardcore rider, dont bother changing fork oil, save up a bunch, get cartridge kit or valve kit

Your the man Dave!

I can drain my engine oil via a drain plug. My MC forks don't have one, so it is not likely it is going to get changed unless it starts to leak.

Thanks Dave - many a question answered! 👍🏻

Thank you for the video, it was just what I needed!

Im about to change the oil of my monster 821. The fork feels too soft specially during breaking (i enter the track casually). I thought of changing the forks to andreani adjustable springs but i might just change the oil from 7.5 to 10, save some momey and try to buy a track bike soon haha. Awesome videos Dave. On point.

Hi. My motorcycle uses semi 10w40 oil. I have in a quart a mix of liqui moly, Motul and Wolf Belgium semi synthetic on excedent from previous bottles when changing oil. Can I use this tree brand mix with identical API and JASO specs? Thanks in advance..

Okay so i'm gonna send my bike over to the US for the annual service.. Worth the cost of shipping for Dave's brain

Dave, if the suspension was dialed on old fork oil you have to make adjustments to the rebound when you replace the oil (using the same viscosity) You should open the rebound or close the rebound (1/4 to 3/4 of a turn as you mentioned in your rebound video) ?

dave.. among other machines. i also ride a 2008 yamaha royal star venture..30k miles on it when i bought it in october 2021..my 3rd venture since 1986.. there is not much of a selection of fork springs and no selection of shock spring upgrades.. I upgraded the springs on my 86 venture and it transformed that machine into a much better handling machine that I did not need to use air in the suspension after the upgrade.. my 2008 venture only has air pressure adjustability… no spring preload or damping settings to juggle. So: The forks max pressure is seven psi The shock max pressure is something like 40 psi I realize that air is the least desirable type of spring to have in a motorcycle suspension.. practically Stone Age.. so:- even if I could buy upgrade fork springs..would it be just as effective to simply stick with air pressure instead of changing fork springs, Since i cant upgrade the shock spring to have balance front to rear?? I do not carry a passenger. This is a rolling lazy boy..no hurry..I do not sprain the speed limit even on the Interstate roads..But I am used to better suspension on my sport bikes, I just had a GL1800 Goldwing , I upgraded the fork springs and the shock spring to Progressive brand when I change the fork seals and bushings and fork oil.. I bought the gold wing which was a 2002 in 2018 with i’m only 13,000 miles on it from the original owner. It still had the original tires on it. The suspension was shot because I believe it sat on the side stand it’s whole life and the springs were just tired, they felt limp, and that machine did not have air suspension.. so do you think it’s a waste of time to install aftermarket fork springs, I think there’s one company, traction dynamics that offers a set of fork springs for my royal star venture, but I’m still stuck with a standard shock and no option to change the rear spring.?? Can you advise me on the weight fork oil I should use? Possibly the height from the top of the compressed fork with a cap off? Without the spring in it?

I have a technical question that I can't find a definitive answer to: If high shaft velocities are causing spiking events, does a thinner oil with less damping port orifice area move the spiking event to a higher shaft velocity, if the damping at lower velocities matches thicker oil with greater port orifice area? ie is thinner oil with slower damping settings better than thicker oil with faster?

I have a feeling that my 2012 ER6n forks are too harsh/stiff when I ride on uneven road. Too bumpy. On manual, forks use 10w kyb g10 and I've not yet change it now at 20.000+ kms Lol... I know it's time for oil change. So, before I change my fork oil... My question is: What is your recommendation for oil viscosity to make my bike more rideable/comfort? Should I change to thinner (like 5w) or stick to factory spec (10w), or change to thicker (15w)? I am 80-82 kgs man (is it heavier or lighter side?) Thanks!

what are the best brand fork oil manufacturers? or isn't that important?

Good advice thanks.

Love that movie. Perfect reference

Out of sheer curiosity... As you stated elsewhere, racing forks typically use 5 wt. Is there any advantage to using a 5 over, say a 10, with correspondingly larger orifices and softer shim stack?

a mechanic told me a thicker oil could damage the pass of oil in the valves. that's true?

viscosity is helpful unless you have a Hardley Davidson. type B? its 5-20wt depending on the harley group. i have 10 and have dented the fender bottoming out. yeah the bike is 34 years old. going with new springs and maybe go back to 15 vs 10wt. may go 20. thanks for the info.

Nice advice. Thanks Dave.

Flipping the bike upside down to fill the fork drain plug is hard

finally after 45,000 miles on my cbr, it's finally leaks, no way im chaming every 6000 miles.

Great video! I am going to be changing my fork oil soon and this video had me thinking. I looked up a chart and there was two different Viscosity Indexes (VI). There was "Reported VI" and "Recalculated VI". What mean what and which should I be looking at? Thanks so much in advance!

Hi Dave, I’m new to your channel. Can’t get enough of it. Quick question, my 09 Daytona 675 (NOT the R model with Ohlins) has had the cartridges changed to KTech’s by the previous owner. Should I use the manufacturers recommend oil or contact KTech to see what they recommend? Btw I’m 75kg and the bike is mainly used for track days. Thanks in advance 👍🏼

A Dave Moss app huh? That's awesome

Hey Dave, i have an 04 GSXR1000 that i have to put new fork oil in. It had Dexron III in it, which was pretty good, i don't have access to fork oil nearby, so which would be better.....Hydraulic Oil, or ATF, and which one? P.S. great videos by the way, yours was the one i watched when i did my first ever fork seal change lol.

You haven’t really used Viscosity Index correctly. It’s not really related to the WEIGHT of oil, but to the degree to which oil viscosity changes with temperature. A higher VI changes viscosity less under temperature change, and is therefore a better oil and costs more. WEIGHT of the oil is measured by Centistoke, and the traditional 5w, 10w etc measurement is meaningless for a fork oil. Good manufacturers like Motorex publish the Centistoke data, so find out your OEM Centistoke and go heavier or lighter from that. For any given Centistoke choose the highest Viscosity Index to get the best oil.

Can someone tell me what happens if you put chain oil in your forks

Screw suspension, this guy should be narrating documentaries instead

Wish it were easier on the Duc Enduro 1200 to service it myself.

I have found forks to get very dirty over time. I am always surprised what I clean out come rebuild time

It's Viscosity Improvers what's breaks down in engine oil. But you don't have VI's in fork oil. So fork oil does not break down, does it? Or maybe not as fast as engine oil. On that basis 6k fork oil change interval sounds too frequent to me..

This may be basically yelling "jehovah", but... Is there a reason AW 32/46 hydraulic oil should or shouldn't be used in motorcycle forks? My older bikes have simple damping rod forks and I'm servicing them and fine tuning them with AW 32, 46, or a 50/50 mix (SAE 10w, 20w, or 15w respectively) since fork oil is expensive (for me) to experiment with and I have a very hard time finding enough of one brand in different weights. It seems to work perfect but I do wonder about long-term damage to sliding parts. BTW, thanks for posting these videos, they are a godsend to a motorcycle noob like myself.

I'm in an awkward position. I've got a set of forks that long ago belonged on some 70s bike, and put them on my 60s bike. Works pretty good! Except the oil smells like death. No idea what bike they were from, so no idea what the recommended viscosity is, or what viscosity is in. I guess we'll just have to take a stab in the dark and see what happens. Lol

I just love your videos and I've learned so much! Thank you! Small Q.: Would mostly "2 up", combined weight of 150kg, riding only during summer, be a sufficient reason to go from 10 to 15? My bike has had lame suspension from stock, but I've upgraded the factory monoshock to Welbers 640, and front fork springs to progressive, but kept oil viscosity of 10 as per manual .. handling has massively improved, but I can still see some room for improvments .. so 10 to 15? 🙂

Anyone been running motorcycle 5WT fork oil on MTB? Fox is recomending teflon infused 5WT, but similar motorcycle 5WT fork oil is 1/3 the cost.

Buy my manufacturing didn't mentioned the viscosity grade for my Aprilia sr150 scooter....so I'm confused 🤔

I'm running a wr250f and works well. I run it at the track sometimes but after I blead the forks the air came out and now they bottom out some times it calls for number 5 .. how high can I go to help out but not make them to stiff for offroad

Nice 1 Dave👏👍Just a quick question I’ve just purchased a 50 year old Fantic Caballero TX 96😉and on the Instructions on the little Tank Bag it recommends FIna Solna 32 and obviously this is long gone😱 So I was looking at some of the Viscosity Charts and I think 10wt is the nearest equivalent for this, but I’m not a Lightweight Person Lol and was wondering if a 15wt would be better for me and Living in the UK 🇬🇧 it doesn’t get that warm well apart from a couple of weeks that is👍

What would you suggest for a guy that's huge like myself for fork oil weight.. 6'2 305 street and mountain riding on a zx14... Love all your videos useful info.

Sir David. Currently i have a yamaha nmax 155 scooter. I used motorex 10w-30 fork oil for my front fork. I like it. What can you say about the fork oil i used? I refilled it with standard service manual recommended fork oil volume.

Dave moss you look like hulk hogan

I’m 165lbs maybe 15 lbs more with gear. I used a 10w oil. Wondering how bike will handle I will be using it in motocross. I’m a class C rider.

So if I’m 185 pounds I guessing I should be using a thicker oil

Hii Dave am having some questions for you that may help me aloot: 1st ,fork oil is atf fluid???I know atfs have kinda inner types mercon II ,mercon 3 ,mercon v ,type F ,also there are steering fluids and such , why this question?? Well I noted some fork oils are red,green,sometimes even blue (I love this one) and also amber and clear colors but ofc color doesn't mean anything than the viscosity at 40 and 100c so thing is....can I use this atf oil in my suspension???will it destroy the seals or the stanchions coat?? Cuz if they're in the viscosity range in my fork manual they're supposed to fit good right?? U may wondering why would I change fork oil with atf, well in my country a bell ray fork oil being imported would cost like 100$ plus taxes but atf would cost 4-5$ in prolly valvoline ,Amalie,castrol,amsoil etc brand and also some steering fluid brands too for 2$ ish so since u are the oil guru I thought in asking u cuz like motorbike forks I wanna use it in hydraulic mountain bike forks cuz mtb lubes comes in even small packages with the double the price even in USA so in order to protect my forks I got immersed in all this oil quest cuz since now I used motor oil for the stanchions but I didn't touched the cartridge yet but hey there are some atfs that would match the viscosity fairly close to sae 5w-10w just a lil bit up or down for a few cst's I hope u can help me Dave good wishes 😁

I have in told ( by who 😀) that 10 weight motor oil works fine in shocks. Your opinion?

10 s1000rr , 185 lbs rider. Manual says sae 7.5. Recommend plz? (Maxima fluid ideally)

Thank you sir

the bike weighs 167kg and is a 200cc tour bike. i weigh 110kg and my luggage weighs another 20kg would it be wise to go for a denser oil as the year round temperatures dont drop below 30 c and goes above 40 c. yearly once it visits the mountains where the temperatures drop below 0 c?

I have a 2006 zx10r and when I ride I can feel every little bump in the road and the forks seem fine no.leaks could the oil need to be changed

What if we used 5w in one fork and 2.5 in the other. Or 10 in one and 2.5 in other...? I bet pros tune shit that way. If SFF forks can, why can inverted kyb do it..?

RIGHT!

Does leaving a smaller air gap or more oil equates to same result such as higher viscosity?

I have a 2004 Kona Caldera. My question is what kind of suspension oil do I need? I'm currently getting my bike powder coated and had to take everything apart so my front marzocchi bomber shocks are completely taken apart and drained. My local bike store said I needed a specific oil but wouldnt tell me what kind and to find out myself. And what kind of grease also?

hey Dave, I bought a 10N/mm (1kg/mm) linear springs for my CBR1100XX, weighing 100kg in gear, I'm wondering which oil should I use? The manual recommends Honda SS8 which is a 36 centistokes oil, should I stay within these specs or go lighter? Also, the fork spring manual advises 140mm air gap, Honda says 142, I presume both gaps would work but there's no mention is the air gap measured with or without springs inside? Thanks a lot

Hi i have yz250f 2008! I am 88 kg I want replace the old fork oil! I need buy the kayaba 01 fork oil or I can buy another cheaper? What you suggest me w?

boss is it advisable to use 2t as,fork oil

What is the difference between fork oil and fork fluid? Maxima has two of them so which one should i choose? (my bike has 31mm telescopic forks)

Hello Dave, I'm about to change Fork seals and dust seals - i'm kind of trying to figure out what oil to use, Bike is CBR600RR year 2006, in service manual I found that they recommend Pro Honda supension fluid ss-8 (google it a bit, it should be 10w, as Motul recommends too). Fully equipped i have around 77-78kg, and I was thiking about putting in Silkolene PRO rsf 5w(viscosity index 372) which is semi synth by their specs. Or maybe try to go Motul Factory Line light/medium(viscosity index 131) 100% Synth? Thank you for your help! :)

Excuse me what's the difference between fork oil 10W and engine oil 10W - 40. Thanks too much

Hi Dave. Love your videos man. I have an 09 Speed Triple w Racetech springs and valve kit and 5wt oil. I'm 225 lbs w out gear. Aggressive street riding, and day trips mostly. U think I should bump the viscosity up during the summer to help damping? Thanks, Keep up the good work. Cheers

Dave interesting video thanks for posting . I have ohlins forks on rsv1000r. The forks bottom out even when I turn on the preload. Would putting a 2.5 weight go some way towards combatting this problem without new internals.? Also will it cause me problems when powering out the bends? Thanks in advance.