Topic: Found fork oil per Honda recommendation SAE 10W-30 - NOT engine oil

[PeWe]

I've searched around the forum here and it seems to be confusions about fork oil recommended in the Honda manual that clearly states Fork oil SAE 10W-30, 220-230cc (7,0-7,3 ozs) in each leg. Some use engine oil that is lubrication oil. I can understand that ATF or Hydraulic fluid might be an alternative to fork oil

Motorex has fork oil 10W-30 so my bike will get what Honda specified 40 years ago  Bought it today
http://www.motorex.com/index.cfm?oid=1147&lang=en&webtoolDbTemp=eintragDetail&kategorieId=12&eintragId=98

[LesterPiglet]

And for anyone in the UK....
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_221375_langId_-1_categoryId_165507

[PeWe]

And for anyone in the UK....
http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_221375_langId_-1_categoryId_165507

... a little bit cheap... I had to pay £15,75 at a local dealer here :-)
I hope it will work fine when it might be better alternatives since Honda wrote the manual.... development in progress...

[bryanj]

I think you are missreading the manual in its Japanese to english translation,

What Honda mean by Fork Oil is the oil you put into the fork NOT a specific type as when the manual was written there was no oil specificaly made for forks but there is now and it is worth using

[PeWe]

Interesting about "fork oil". When I replaced the fork oil for the first time end of 1979 it was called Fork oil on the bottle. Engine oil was not used in the forks.
It would be nice to find very old Honda document specifying the oils in detail, engine oil, fork oil.

I found this explanation in the Honda manual that is not that old when it also describe K8. Here is "high quality ATF" specified.  See attachment.
The amount is different if it is dry forks or just a refill. ~7,5 ozs 220-230cc (dry)

I guess that fork oil is a later name of the fluid in the forks, earlier ATF. 

Maybe old timers working with the CB750's in the early 70's can add some of their experiences?

[Lostboy Steve]

I honestly love my maxima 10 fork oil. Its made for forks. The 10wt has specification like that of Harley Davidson Type E. In my opinion any new sportster has a very similar front end to a cb550. Anyway to each his own. The other major difference between P/S, ATF, and Fork oil is probably the anti foaming qualities.

[w1sa]

It's the viscosity range of the specified oil that is the important feature of the oil quoted for forks etc.....If Honda quoted 10w30, then they are saying, that particular viscosity range is what's reqired ....you dont generally have ATF in the same viscosity range as 10w30, so specifying ATF for a different model is generally saying a lighter oil than 10w30 is required....the viscosity at operating temperature is important to the damping rates in the forks..........e.g.  a typical 10w30 viscosity @40c could be say 75 to 90, where as a typical ATF would be more like 35 to 45...and, interestingly a Fork 10 oil (for most sellers)is equivalent to a typical ATF viscosity

Mostly everything else about the oils is not dis-similar...anti foaming, seal protection/swell, corrosion resistance, sludge control etc are all important to most oils used in machinery/hydraulics/engines/drivetrains...some are just more specialised than others...or claim to be!!

[Dream750]

PeWe, you bring up a good point.

The early Honda-published 750 K shop manual does specify a SAE 10W-30 or its equivalent. Honda later published shop manual supplements which changed this specification to automatic transmission fluid for the K1 and up bikes. As an example, my 750 K4 owners manual also states to use automatic transmission fluid. I suspect this fluid change came about when Honda went to the double lip style fork oil seal beginning with the 750 K3 and updated the K1 and K2 as per this service bulletin:

http://manuals.sohc4.net/CB750SB/750_41.pdf

According to my Honda shop manual with the supplements, the 1969-70 K0 bikes still use SAE 10W-30 and the 1971 and up K bikes use automatic transmission fluid. Fast forward to modern times ... I use 15W fork (specific) oil for my best suspension performance and feel.

750 K4 owners manual:

[ekpent]

I'm still in the ATF club over here. Never have tried real fork oil. Should take Dreams suggestion sometime and give that 15w a try I quess for comparison.

[Dave Voss]

Just about any oil will lubricate and damp the forks, but the type of oil used determines how predictable the fork's behavor will be with light versus heavy loads, on smooth versus rough roads, and in hot versus cold climates.  Oils labeled and sold as 'Fork Oil' are formulated to remain stable across the specific conditions that forks subject the oil to, and so are the best choice.  For example, fork oil will allow the suspension to perform better at the end of a long ride on rough roads, whereas typical engine oil would allow the suspension feel to change quite a bit more during the same ride.  The anti-foaming quality of fork oil is important, and while 10W oil is equivalent to the recommended viscosity, I've found that 15W oil provides better performance, especially with dual disc brake conversions.

[LesterPiglet]

In my 550(Haynes) manual it states: "Fork oil grade......ATF or fork oil."  Pretty vague.

[PeWe]

So, the SAE 10W-30 in the old Honda manual...? Not "fork oil"?
The last fork oil I bought late 80's was the same as I bought yesterday. I found a half empty bottle with 550cc. I was sure I had disposed it years ago...

[Dream750]

Here’s how the early 750 shop manual shows the specification of SAE 10W-30 being used in the forks. The second image also comes from within the (Group 11) steering and front suspension chapter.

Click/double click the images for largest view:
   

[KRONUS0100]

interesting, i just changed the fork oil in front end of my 76 750f with the 76 gl1000 forks.........7 ounces of 10w30 oil each fork. dont have the book in front of me at moment, but pretty sure it says 10w30 oil for forks.  used to use atf and it leaked eventually even with the leak proof seals.

[CBNJ74]

I followed the village elders on here and went with ATF when rebuilding my forks. No complaints here.

[PeWe]

Anyone that have tested different oils and viscosities in a CB750 and came into a conclusion regarding a good oil/viscosity?
My bike had problems last time after installation of progressive fork springs. I'll drive without the appr 1" plastic spacers on top of the fork springs I used last time soon 23 years ago. The bike got heavy fork wobble at appr 170km/h despite steering damper.

[CBNJ74]

Anyone that have tested different oils and viscosities in a CB750 and came into a conclusion regarding a good oil/viscosity?
My bike had problems last time after installation of progressive fork springs. I'll drive without the appr 1" plastic spacers on top of the fork springs I used last time soon 23 years ago. The bike got heavy fork wobble at appr 170km/h despite steering damper.

I ran mine without the spacers. No way hell I was going to be able to get the fork caps back on with the spacers in.

[jamesbekman]

It went to ATF due to its anti foaming properties that the newer fork oils have now as well that "mineral spirits" did not have back then.

[Nic]

We used atf back in the 70s n that's what I'm using today. I had a heap of it in the shed for years so I figured why spend more money here.

[scottly]

There is a Honda service bulletin regarding the switch to ATF on CycleRanger's sticky thread at the top of the main page. It's in reply #18.

[PeWe]

There is a Honda service bulletin regarding the switch to ATF on CycleRanger's sticky thread at the top of the main page. It's in reply #18.

Thanks!
I see that engine oil could have been used then.

"ATF is superior to 10W/30 motor oil for use in telescopic forks, because it does not become as aerated as motor oil during fork operation. Also, fork oil seals tend to have longer service life when ATF is used."

[dave500]

in these old forks, with their more or less short travel road bike suspension, on more or less smooth roads you could use more or less anything,,try what works,what feels ok,,if its too stiff try thinner oil,,late model long stroke suspension dirt bikes will really need a proper fork oil,,its one extreme to the other,,you aint gonna foam up the wrong oil in these forks unless your a crusty demon?riding the wrong bike for the job?

[chewbacca5000]

I love it another oil thread!  Maybe I will start an wheel bearing grease thread.  Just kidding.  I thought Honda wrung the oil out of fish directly into the forks when they left the factory.  At least that is what the stuff looked like when I dumped it out of my CB500.

This a good thread.  Hope I went with the right stuff 10 weight blue fork oil kinda pricey.

[dave500]

its whale oil.

[LesterPiglet]

Whale oil be damned to be sure.

[dave500]

i think up untill the late 60s or 70s,,the GM automatic dexron spec oil contained whale oil for its anti rusting properties,,ive never seen a rusty whale so it must be true?

[brewsky]

GM used it in anti-slip rear ends for clutch chatter elimination in the 80's.
 
They must have forgot to put it in my new 85 Trans Am, cause every time it rounded a curve, it sounded like the rear diff was coming apart.

The fix was an ounce or so of "whale sperm" as the tech called it. He said it had been banned and once it was used up there would be no more!

I didn't ask any more questions!

[dave500]

a bit off topic but still honda and oil,,my mate has an early 2000 honda cr-v car,,it had a funny noise in the rear end only when turning,,hes mechanic said it needed new oil specific to these units,,we couldnt get it anywhere,,no where supplied this oil or its equivelent,so he bit the bullet and bought the bloody expensive correct oil from honda,its like water its that thin,,the stuff that came out wasnt smelly and was clear,,the stuff that went in wasnt smelly and also was clear,,the noise went away??i was amazed!

[chewbacca5000]

i think up untill the late 60s or 70s,,the GM automatic dexron spec oil contained whale oil for its anti rusting properties,,ive never seen a rusty whale so it must be true?

I guess you see the friendliest people driving a honda unless you are a whale.

[Muckinfuss]

I've been using ATF not only in forks, but in bikes I've owned with wet primary case/clutch designs.  Never, ever had a problem with either.  Fork oil viscosity is primary in managing the damping characteristics designed into the fork.  Of consideration is the weight being carried by the bike.  Heavy means different damping is necessary than light.  Anti-foaming and shear are also considerations, but almost any ATF is over engineered in those...so not to worry.

Not all ATF is the same viscosity.  Perhaps this will help:

VI is viscosity index and speaks to viscosity stability as temperatures change. Higher is more resistant to change with temperature.

Transmission fluid viscosity is normally rated at 40C, while engine oils are rated at 100C. And, as already pointed out, the viscosity scales for gear oil and engine oils are different.

Viscosities are in cSt - centistokes - and are essentially a timed flow thru a cup with a hole in it, just like paint.

VI Vis@40C Vis@100C
.............8.3 = Honda CVT Fluid
.............7.6 = Mobil 1 Synthetic ATF

198 33.5 7.5 = Redline D4 ATF Dexron III / Mercon / API GL-4
.............7.4 = Mobil 1 Synthetic Dexron/Mercon
197 32.5 7.2 = Redline Synthetic ATF Dexron II / Mercon
.............7.1 = Mobil 1 Synthetic Multi-vehicle ATF
138 40.5 7.1 = AMSOIL Ford type F auto trans fluid
168 37.4 6.8 = AMSOIL Automatic Transmission Fluid ATF
..........5.5-6 = Ford Mercon SP

[Jerry Rxman Griffin aka MuthaF'er]

I'm thinking along 2 lines here. Anti-foaming and better sealing through slight rubber expansion with ATF or fork oil.