Author Topic: 15W valvoline fork oil  (Read 1649 times)

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Offline wastegate

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15W valvoline fork oil
on: 02 November, 2020, 04:09:49 PM
Someone asked if I had done this change in the original posts I made at the start of the year. Around 11 from Halfords and final  piece of the suspension upgrades ( Hagon rear shock sprung for my weight and 25mm raised rear ride height, mid rise renthal lower bars and forks 10mm up through the yokes ) after putting on nearly 5K miles since lockdown. Well worth the effort to change it and now it handles really, really well over bumpy roads, long fast sweepers and the 100's of Milton Keynes roundabouts. Changing direction deep on the brakes doesn't confuse everything and it holds it's line naturally, no running wide or pushing/pulling on the bars needed at all. Down to about 8mm unused front tyre which too me is much safer than a tiny contact patch with 1" unused each side that mine was as standard. The narrow rear on a big heavy bike means its lovely and light to change direction but would stop me taking it out on track.

In the scheme of things and in my opinion a relatively cheap outlay turns it into a great sports-tourer and very capable and quick do anything bike, if that's what you want from it - but everyone has their style of riding and what they want form the bike may be totally different, so its only one approach.


Offline Art

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Re: 15W valvoline fork oil
Reply #1 on: 02 November, 2020, 05:01:10 PM
Happy Days

That's what I have in mine 15W Valvoline Synpower fork oil and 1L is more than enough to do both fork legs.

Now that most of these CBF 1000's are on their 3rd, 4th or more owners front fork oil is an area often skipped in the service schedule, get on down and dirty and get that fork oil changed. We know the Honda recommended fork fluid is Honda ULTRA CUSHION OIL 10W or equivalent but we choose to be different for a slightly firmer ride.


Offline Shed

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Re: 15W valvoline fork oil
Reply #2 on: 02 November, 2020, 06:15:43 PM
As with the engine oil theme on another current thread, there is no agreed standard for what weight fork oils are, so one manufactures 10w can be the same as another manufactures 15w, and so on. Centistokes is the key here, a centistoke, or cSt is a measure of viscosity. I wrote about it here, 2 1/2 years ago - where does the time go?!  :005:

Art, your Valvoline, is ISO VG 46. ISO (International Standards Organization) VG (Viscosity Grade) for that Valvoline oil is 46 - which is the cSt, (centistoke).

*Originally Posted by Shed [+]
I personally think there are many variables to what oil 'suits' you. Your personal weight, the weight you'll be most likely carrying around, your style of riding, the temperature, what the roads are like where you are riding, what 'feel' from the front end you personally like, etc etc. Simplified, a lightweight rider just going up & down the motorway is most likely going to be fine with low weight fork oil, whereas a more heavily set rider blasting around the lake district may find a slightly heavier fork oil will give a more comfortable ride. Ultimately, it's all going to come down to personal preference. It's your bike, and you're the one riding it. You know what you like best. Fork oil is extremely cheap, so if you don't like one, you can easily change it for another weight oil within a couple of hours.

The labelling of the fork oils, 7.5W, 10W, 15W, 20W, should be considered a 'rough guide'. Bear in mind one manufacturers 10W or 15W fork oil isn't necessarily the same as another manufacturers fork oil. If you want a truer comparison between the different manufactures, the sae 'weight' of the oils should be compared by their respective viscosity index number by way of a testing method know as Centistoke testing scale, i.e. centistokes (cSt). If you are having trouble sleeping, fill your boots with that one.  :800:

The manual states the Biffer's recommended oil is 10W using Honda's own 'Ultra Cushion Oil' brand. This oil has a cSt of approx 35. Compare this with Castrol fork oil 10W, which has a cSt of 32, or Rock Oil 10W with a cSt of 32, so both very similar to the recommended Honda oil. However, Silkolene Pro RSF 10W has a cSt of 47, or Bel-Ray High Performance 10W with a cSt of 53 - so despite these fork oils still being labelled as 10W oils they are both a far thicker oil than the Honda one, much less viscous, and therefore 'stiffer'.
Conversely, Putoline HPX 7.5W has a cSt of 33. So despite being labelled a much lighter 7.5W oil, it is actually almost the same in viscosity as the Honda 10W oil.

This comparative table gives you idea on the differences, even though they are the 'same' weighting. Yes, it's 10 years old but it illustrates the point nicely, and many of these oils are still available for your enjoyment. Enjoy:

Last Edit: 02 November, 2020, 07:05:55 PM by Shed


Offline raYzerman

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Re: 15W valvoline fork oil
Reply #3 on: 12 November, 2020, 01:59:53 PM
My experience on the Mk1.... have rear Ohlins shock with I believe a 900 lb. spring.  Front fork springs are 1.0 with 10W fork oil (done by previous owner).  Damping was not cutting it, so increased preload 22mm initially with new spacers.  Still not good enough, not enough damping.  Changed fork oil to BelRay 15W (~50 CST), kept an increased preload of 15mm.  Dramatic difference, these bikes need that 15W-ish fork oil.
There's not a lot more you can do with the stock fork valving without going aftermarket... ideally new cartridges with adjustable damping.  BTW, I weigh 200 lbs. without gear.