Fork oil

[Sonataman]

Looking at the Spectro oils, the 20w has a 40c rating of 72.2 and a 100c rating of 8.5 and a VI of 85 ([censored] I know). In a bid to have a more consistent feel from my fork I was wondering if an oil (Mobil 0w40) with a 40c rating of 75 and a 100c rating of 13.5 would work.

I know ambient temps don't usually get above 104F so that would be the ONLY time it would actually feel stiffer. But then again, do you think the first oil will feel much different at 50F than it does at 100F?

Had not thought of this until today when playing with forks.

 

[AVB]

I am not sure what the operating temps of suspension components are, but they do create heat. On the street the temp should be stable enough that you will not notice a difference, unless it is really cold.

By the way it would be stiffer when cold, not hot. I would stick with the fork oil, there is a reason they don't sell motor oil as fork oil.

 

[sunruh]

no bike get the fork oil "hot".
not even the winner of an AMA SX race.
forks have way too much surface area and volume of oil to disapate the heat.
now a shock is a completely different story.
on a street bike, i dont know if it can be overheated with normal riding. get a really big bike going fast in twistys and maybe they can.
in the dirt...oh heck yeah!
its all about shock shaft speed

 

[LotI]

Motor oils have a bunch of stuff that forks don't need.

Look to some of the ATF's for something to try. When I changed fluid in my VFR forks this spring I added some Redline D4 to some leftover forks oils I had and it is way too stiff. I think Honda recommends a 5w but at my weight I found a 7.5 wt is better.

With forks the two specs that are most important to me are the 40C viscosity and the VI. As mentioned before, forks don't get that hot since they have a lot of surface area and they're in the cooling airstream.

 

[sunruh]

if you want a great forkoil that you can find anyplace

Mobil 1 ATF