I need to top up/replace the oil in my forks but I was wondering what to buy. Looking at Castrol motorcycle mineral fork oil 5wt and Castrol motorcycle fully synthetic fork oil 5wt.
I have read online mineral oil damages seals, But this is generally spoken more generally about mineral engine/gear oil. This mineral fork oil that I have looked at must not be bad for seals as after all motorcycle suspension have seals too.
I dont want to buy the wrong stuff though, so can anyone shed any light on the matter?
Maybe it depends on fork?
I was told only synthetic for my Marzocchi, so use Castrol Synthetic at £7.99 per 500ml off Amazon inc. shipping.
Fork is a Manitou Black Super Air 120mm from 2004.
Fully Synthetic, always.
You want stuff designed for use in MX bike forks. Makes include (but are not exclusive to) Silkolene, Putoline, Rock Oil, Castrol, Shell, Motorex.
I've used Silkolene, Putoline and Rock Oil so far, can't say I noticed any difference in quality between these 3 in use. Silkolene was nifty though cos the oils are coloured differently depending on the viscosity. But mainly I use Putoline now as my local MX bike shop has it in stock for £9.99 a litre...
Ordered 7.5 wt Rock Oil from CRC, for 99p more its delivered and I know its used in lots of bike forks.
Oooh, one thing, beware of forks oils with seal swelling additives (useful to prevent leaks). They can cause the seals to overswell and cause massive stiction on (some?) MTB forks.