Suspension Oil
Browse suspension oil for sale from riders across the UK. Suspension oil covers two jobs in a fork or shock — the damping fluid inside the cartridge, commonly specified as 0W-30 or in fork weights from 5wt to 10wt, and the bath oil that lubricates bushings and foam rings in the lower legs. Manufacturers typically ask for a lower-leg service every 50 hours of riding and a full damper service at a few times that, which is what most of this oil gets bought for.
What is the difference between damper oil and lower-leg bath oil?
Damper oil works inside a sealed cartridge, forced through shim stacks and needle valves, so its viscosity directly sets how fast the fork compresses and rebounds. Bath oil sits in the lower legs and only has to lubricate the bushings and keep the foam rings charged, which is why some are semi-thick fluids rather than plain oil. Putting the wrong one in the wrong place gives either a fork that damps nothing or a cartridge that will not stroke properly.
What do 0W-30, 5wt and 10wt actually mean?
Fork weights are not a standardised scale — one brand's 5wt can be thicker than another's 7wt, because the number is a trade description rather than a measurement. The figure worth comparing is viscosity in centistokes at 40°C, printed on most bottles. In practice you match whatever the fork or shock manual specifies, since the shim stack was valved around that fluid; a heavier oil slows both compression and rebound and cannot be dialled back out with the knobs.
Does a fork need grease as well as oil?
Yes, and they are not interchangeable. Wiper seals and foam rings want a slick, low-friction seal grease rather than anything from a general bearing tub, which is why fork-specific products exist alongside the oils — see grease for that side of it. Chain lube has no place anywhere near a stanchion, and the products under chain lubes will attack seals rather than help them.
How much oil does a service use, and does it keep?
A lower-leg service uses only tens of millilitres per leg, so a 1-litre bottle covers many services and the per-service cost is small. Sealed bottles keep for years; an opened one wants the cap on tight, since moisture and workshop dust in the fluid end up circulating through a damper. Oil drained from a fork comes out dark grey with bushing and anodising wear in it and is never reused, however clean the last service looked.
Is it worth servicing suspension yourself?
A lower-leg service needs little more than the correct oil, new foam rings and seals, and a way to hold the fork — the oil is the cheapest part of it. A full damper rebuild is a different proposition, needing bleed equipment and sometimes brand-specific tools, and that is the point at which sending the fork away makes sense. Names you will see on bottles include Fox, RockShox, Motorex and Maxima; the wider category sits under lubricants.