One fork oil to rule them all?

For the first time, I’ve got a mixture of Fox and Rockshox-equipped bikes to look after. Is there one oil for lowers services that would do the job for both? Would Fox Gold 20wt work well on either, or should I be shelling out for the recommended stuff?

Simple anser is yes, Fox 20 works in the lowers of Rockshox. It actually works really well and the only thing I prefer to that is Supergliss 100.

More complex answer is a question. What dampers to you have in each? If it’s the more recent self bleeding dampers with the spring backed IFP, you need to use damper oil on that side as they will ingest oil from the lowers (then spit it back out the self bleed feature).

Cheers. The Sids are new, all the Fox stuff is pre 2019.

I think the SID is still using the RaceDay damper rather than the Charger 3 so shouldn’t be an issue.

Certainly, if the manual says to use the same bath oil both sides for any particular fork, then 20wt gold both sides is fine.

Thanks!

Shell Rhodina BBZ grease for lubricating seals/air shafts. Any brand 5w30 fully synthetic engine oil for lowers. Proper fork oil for dampers.

Dampers are choosy, lowers aren’t, is the short answer. It’s not completely true- some fork oils have more or less seal swellers, some don’t, some seals are more temperamental about oil though that gets less and less in quality forks these days, stuff like that.

But basically dampers really depend totally on how the oil will behave in order to work, as they basically all work by squishing oil through holes of varyign sizes (and that’s also very hard on the oil, fork oils are really durable).
Lowers fundamentally just want lubricated. I used to use diesel engine oil in my oldschool lyriks and boxxer, worked better than the recommended oils, less sticky.

Stendec I use to use even if I messed up amounts of heavier weight in old bombers trying to alter too much reb damping

User error obvs though the oil itself was fab

+1 what Northwind mentioned.

Some like DVO do not even like Maxima type oils or even shock lube around seals as can promote foaming and wear iirc

Formula’s FX lowers oil is thicker and seems more sticky than RockShox’s 0W30.

Motorex. Both for the lowers and dampers, performs much better than Fox or RockShox original oils. For lowers something like 10-15 W, for dampers it needs to be the correct stuff and you cannot get by with just one thickness.

Fox’s Gold 20 is horrible if you ever ride in temps close to 0 C. It goes really thick and sticky, and if you ever ride in sub-zero, it makes the whole fork feel stiff.

Here is a site that has a nice selection of charts showing what oils work for substituing which original oils –

https://www.shockcraft.co.nz/technical-support/suspension-oils/fork-oil-selection-charts

For Fox – https://www.shockcraft.co.nz/technical-support/suspension-oils/fork-oil-selection-charts/fox-oils

For RS – https://www.shockcraft.co.nz/technical-support/suspension-oils/fork-oil-selection-charts/rockshox-oils

Considering the small volumes of oil required in forks, you may as well stick to the correct type and brand, safe in the knowledge that you’re not hindering any future warranty inspections.
Your SID will only require 10ml of Maxima Heavy in each lower leg, and the Fox fork (I’m unsure what model you have) will generally require 10-30ml of 20wt gold in the left and 40ml of 5wt Teflon in the right (assuming a GRIP damper)
You could easily equip yourself with enough fluids for 4 lower leg services for less than £20. There’s reputable sellers on Ebay selling genuine fluids in these volumes.
Hope you find this info useful