Rockshocks fork oil

[Warren Melissa Go Riding]

Hi Guys,

 

Doing a lower leg service on my lyric select plus. Oil required is 0w-30. I have a full bottle of 5wt Motul suspension oil at home. I know its not the same but would it work?

Appreciate it.

W

 

 

[fanievb]

it wont

[Mongooser]

You could on the older forks get away with it.  Newer forks requires the brands overpriced oil.  It'll work but there is chance your adjusters and fork will feel slightly different 

[BaGearA]

Yes it will work but it won't cling to the bushes and stanchions as well as it should and that's the sole purpose of lowers oil 

[Thermophage]

There are, generally, two types of oil in a fork and they serve a different purpose.

Lower leg oil mostly for lubrication and is generally not marketed as "fork oil" -- i.e. the stuff you have there.

And then there is damper oil, which has poorer lubricating properties but better damping characteristics - i.e. what you have.

For lowers oil I've (and many a bike shop) have used the Castrol Magnatec Fully Synthetic 5w30 (you'll have to check, there are multiple threads on here about it) - cheap and available at Midas. Some forks use a different oil in each leg of the lowers, so just check service guide

So your stuff will work, but far from ideal and a trip to Midas or wherever to get a more appropriate oil is cheap.

[DieselnDust]

It won't work very well because the 5W motul is hydraulic oil and is not designed to lubricate in the regime required. It will oxidise quickly and lose lubricity well before the 50hrs service interval is up. 

You can use any 4 stroke engine oil for the lowers of SAE 0W-30 to 5w-40.

[Headshot]

Once again a variety of contradictory and confusing posts in reply to a technical question, proving yet again that a forum like Bikehub is not the place to ask such things. ????  

[Alouette3]

Get some Magnetec 5w30 from your local Midas etc

Would avoid fork oil for the lowers. 

There are a couple threads about oil alternatives. Droo will be along shortly with more info

Edited November 4, 2021 by Alouette3

[droo]

7 hours ago, DieselnDust said:

It won't work very well because the 5W motul is hydraulic oil and is not designed to lubricate in the regime required. It will oxidise quickly and lose lubricity well before the 50hrs service interval is up. 

You can use any 4 stroke engine oil for the lowers of SAE 0W-30 to 5w-40.

^

Listen to this guy

[droo]

7 hours ago, Thermophage said:

There are, generally, two types of oil in a fork and they serve a different purpose.

Lower leg oil mostly for lubrication and is generally not marketed as "fork oil" -- i.e. the stuff you have there.

And then there is damper oil, which has poorer lubricating properties but better damping characteristics - i.e. what you have.

For lowers oil I've (and many a bike shop) have used the Castrol Magnatec Fully Synthetic 5w30 (you'll have to check, there are multiple threads on here about it) - cheap and available at Midas. Some forks use a different oil in each leg of the lowers, so just check service guide

So your stuff will work, but far from ideal and a trip to Midas or wherever to get a more appropriate oil is cheap.

^

This guy also, but the last guy was more specific ITO what to buy and why.

[Headshot]

21 hours ago, DieselnDust said:

It won't work very well because the 5W motul is hydraulic oil and is not designed to lubricate in the regime required. It will oxidise quickly and lose lubricity well before the 50hrs service interval is up. 

You can use any 4 stroke engine oil for the lowers of SAE 0W-30 to 5w-40.

A fork lower leg is not an internal combustion engine - well the legs pump up and down in the lowers, but its not a high heat lubrication environment.  A rear shock does sometimes get quite warm and arguably are subjected to more stress than a fork. Why does a fork require high spec engine oil over hydraulic oil, which survives for many hours in dampers?

Edited November 5, 2021 by Headshot

[DieselnDust]

4 minutes ago, Headshot said:

A fork lower leg is not an internal combustion engine - well the legs pump up and down in the lowers, but its not a high heat lubrication environment.  A rear shock does sometimes get quite warm and arguably are subjected to more stress than a fork. Why does a fork requires high spec engine oil over hydraulic oil, which survives for many hours in dampers?

 

one simple answer, there very little oil in the lower legs, about 10ml of the stuff.

Car dampers have a lot of oil and they use a hydraulic fluid formulated to work in that environment i.e. a mono grade base oil with a much higher additive content. Because the volume of oil in those units, the oil copes a lot better and survives for much longer since its viscosity does not break down as much since theres very little thin film lubrication going on. Car dampers and motorcycle forks have around 500 to 750ml of oil so the oil runs much cooler and has a lot more additive. Engine oil has viscosity modifier which helps maintain oil film strength when there isn't enough oil, has the highest dose of anti wear and extreme pressure additive that provides protection when the fork is cycled after standing for a period with a higher treat of oxidation inhibitors (very nasty environment these engines). 

Back in the day when we had open bath dampers in MTB forks hydraulic oil worked just fine. But the times they have changed and the best oils to cope with the splash lube requirement in the fork lowers is engine oi or a  suspension fluid that has a high dose of EP, anti wear, and oxidation inhibitors.

Some fork manufacturers are now going full circle back to grease in the lower legs because not much oil is needed and grease provides superior protection at these low volumes.

Open bath, ...different story

 

[droo]

On 11/5/2021 at 10:45 AM, DieselnDust said:

 

one simple answer, there very little oil in the lower legs, about 10ml of the stuff.

Car dampers have a lot of oil and they use a hydraulic fluid formulated to work in that environment i.e. a mono grade base oil with a much higher additive content. Because the volume of oil in those units, the oil copes a lot better and survives for much longer since its viscosity does not break down as much since theres very little thin film lubrication going on. Car dampers and motorcycle forks have around 500 to 750ml of oil so the oil runs much cooler and has a lot more additive. Engine oil has viscosity modifier which helps maintain oil film strength when there isn't enough oil, has the highest dose of anti wear and extreme pressure additive that provides protection when the fork is cycled after standing for a period with a higher treat of oxidation inhibitors (very nasty environment these engines). 

Back in the day when we had open bath dampers in MTB forks hydraulic oil worked just fine. But the times they have changed and the best oils to cope with the splash lube requirement in the fork lowers is engine oi or a  suspension fluid that has a high dose of EP, anti wear, and oxidation inhibitors.

Some fork manufacturers are now going full circle back to grease in the lower legs because not much oil is needed and grease provides superior protection at these low volumes.

Open bath, ...different story

 

Next question, what's your take on using slideway oil? It's what's specced in Ohlins lowers, specifically Fuchs RENEP CGLP 68.

[DieselnDust]

1 hour ago, droo said:

Next question, what's your take on using slideway oil? It's what's specced in Ohlins lowers, specifically Fuchs RENEP CGLP 68.

Slideway oils are good too. Lots of EP additive in those. ISO 68 will also have enough film strength. The viscosity is a bit higher than that specified for a RockShox , but shouldn't be a problem if bushing to stanchion clearance isn't tight.

Key advantage of this particular product is it's blended to shed  water  when maintaining a film of EP additive to help combat bushing wear in the presence of water, and soap since it's compatible with water soluble cutt fluids. A good choice by Ohlins.

I still think a 5W 30 is better because its got a wider viscosity range that is needed where bushing clearance is tight. Forks don' get anywhere near as hot as engines so the lower viscosity range is actually more important than the upper. The multigrade engine has an advantage in being highly stable in shear i.e. when parts are sliding past each other very quickly but a Slideway oil of ISO68 will still be in the sweet spot. I'd say use whichever you can find in the most convenient pack size.

There is a complication in the base oil used for the blending. Because Passenger car motor oil, especially the synthetic variety (group 3 or PAO) will tend to be more stable over time.

Edited November 6, 2021 by DieselnDust

[Hairy]

3 hours ago, DieselnDust said:

Slideway oils are good too. Lots of EP additive in those. ISO 68 will also have enough film strength. The viscosity is a bit higher than that specified for a RockShox , but shouldn't be a problem if bushing to stanchion clearance isn't tight.

Key advantage of this particular product is it's blended to shed  water  when maintaining a film of EP additive to help combat bushing wear in the presence of water, and soap since it's compatible with water soluble cutt fluids. A good choice by Ohlins.

I still think a 5W 30 is better because its got a wider viscosity range that is needed where bushing clearance is tight. Forks don' get anywhere near as hot as engines so the lower viscosity range is actually more important than the upper. The multigrade engine has an advantage in being highly stable in shear i.e. when parts are sliding past each other very quickly but a Slideway oil of ISO68 will still be in the sweet spot. I'd say use whichever you can find in the most convenient pack size.

There is a complication in the base oil used for the blending. Because Passenger car motor oil, especially the synthetic variety (group 3 or PAO) will tend to be more stable over time.

I do love reading you lube posts .................. seriously I do!

[droo]

On 11/6/2021 at 1:54 PM, DieselnDust said:

Slideway oils are good too. Lots of EP additive in those. ISO 68 will also have enough film strength. The viscosity is a bit higher than that specified for a RockShox , but shouldn't be a problem if bushing to stanchion clearance isn't tight.

Key advantage of this particular product is it's blended to shed  water  when maintaining a film of EP additive to help combat bushing wear in the presence of water, and soap since it's compatible with water soluble cutt fluids. A good choice by Ohlins.

I still think a 5W 30 is better because its got a wider viscosity range that is needed where bushing clearance is tight. Forks don' get anywhere near as hot as engines so the lower viscosity range is actually more important than the upper. The multigrade engine has an advantage in being highly stable in shear i.e. when parts are sliding past each other very quickly but a Slideway oil of ISO68 will still be in the sweet spot. I'd say use whichever you can find in the most convenient pack size.

There is a complication in the base oil used for the blending. Because Passenger car motor oil, especially the synthetic variety (group 3 or PAO) will tend to be more stable over time.

Good info, cheers. I didn't think Ohlins would have made a bad call, but not being a tribologist and not knowing any that aren't affiliated to a brand they're selling makes it hard to get an unbiased opinion.

 

The stability would probably explain the 50 hour oil change intervals on Ohlins forks then, which means that 5W30 would be better for the average bike owner who pushes their service intervals to 200+ hours...