Been looking at getting some Enduro seals to replace the worn seals on both my Fox 36 Talas and Rock Shox Pike Dual Airs.

Whilst reading their 'How To' guides on the website they suggest using engine oil (well they call it motor oil but their American) instead of 15wt (RS) or 7wt (Fox) fork oil.

Has anyone done this?

Both forks are out of warranty so that's not an issue.

Do they mean for installation purposes or run engine oil instead of fork oil?

So you are going to buy a seal set for £20 – sp why not just pay an extra £10 for some decent fork oil – i.e. synthetic?

They also suggest buying their slick grease but I just used my old pace RC fork grease instead.

to run it iirc

Because theres not need for synthetic lube in that aplication really? Might even run better with a mineral oil?

I ran engine oil in my forks for years, plenty of motorbikes specify an engine (occasionaly even transmision) oil in their forks as well.

What about wether the seals are a type of rubber that is not designed to be run with a non-synthetic or semi-synthetic oil – i.e. seal rot ? Thats where I am comming from thisisnotaspoon?

they design the seals qed they know what they are talking about

Erm no I mean the internals RR? i.e. not the Enduro ones of course as they are obviously happy with that? JUst a thought as you are advised not to use Mineral oil in DOT brake systems and vice versa?

I do remeber a thread talking about it once before…

Short answer is I dont really know..

As tinas says you can run automatic transmission fluid as its a very similar thing to fork oil as its anti foaming(but the viscocity is guesswork), not sure about how engine oils work in that application, synthetic or not.

They suggest using fully synthetic engine oil 5/40w – which is what I run in The Beast so pinching from my stores 200ml to do the forks is easy.

The first set of forks I serviced was a set of Fox Talas 32's and I filled them with Fox's thick blue seal fluid rather than the oil – becuase I wasn't reading the instructions properly. The forks didn't work properly. Once I had swapped it out for Fox oil the forks worked fine. In fact they were alot plusher and remained so.

I think I'm going to give it ago on the Pikes as I don't 'need' them at the moment.

if its fully synthetic oil I wouldn't thought it'd be a problem but characteristics of the fork may change if the viscosity is no the same 🙂

I read this a while back. I think it makes sense. They still use fork oil in the damper but the 30cc of sloshing oil in the bottom of the legs, they suggest using engine oil. My understanding is that it clings better to the internals ans might actually work better with the hydrodynamic bearings. Not tried it yet though.

The engine oil is for lubrication between the uppers and the sliders. The damper will need the usual fork oil.

+1 LAT – didn't know which side were were taking about sorry 🙂

Now that make a hell of a lot more sense.

Right.

Re-reading the instructions they talk about putting 16cc into the bottom of each leg. And the damper unit isn't opened.

Glad I posted else things may have gone wrong when I change the travel on my Rebas!

I've got Fox 7wt oil already too.

I'll give it ago and report back.

I've used synthetic oil for lubrication purposes in my forks since 2005.

You don't want to use it as your damping medium though. Rather too foamy and thick.

It'd be no use on open bath systems where the damping oil does the lubrication, but most forks these days separate lubrication oil and damping oil so they can reduce the overall volume of both, thus saving weight.

theres nothing specific about synthetic oil, its like saying you have a cabon frame, doenst specidy if it was intended to be a selvet track bike or a 12" hucking freeride monster.

Synthetic just refers to the manufacturing process where the oil is synthesised form other hydrocarbons as opposed to mineral oil which is simply a mixtrue of various crude fractions.

What the oil is used for is more down to its additives. eg gear oil has a high sulphur content and a small ammount of very very long hydrocarbons, these would lead to an almost instant emissions failiure if you ran it in an engine, but does help it survive for 100,000miles between changes in modern car and van gearboxes. Similarly fork oil will have been developed to be as slipperly as possible with the minimum of foaming and to be as newtonian as possible. Somethign stickier is probably usefull in the lowers as you want it to coat the stanchions, but not so sticky that it just clings to the inside of the lowers or actualy creates friction 9remmber gear oil doesnt have to lubricate as much).