Trailer wheel bearing grease
Updated: 23 October 2026
A warm caravan wheel, or a boat trailer just out of the water, raises the same question. Trailer wheel bearing grease only belongs in a hub you can open, on the interval the hub maker prints, and kept off the brake linings. Peter F., editor for DIY supplies, sets out separate cones against unitised hubs, the grease Knott names, and what changes in the water. Hand-packing is on [how to pack a wheel bearing with grease](/hub/diy-supplies/ball-bearing-grease/sub/ball-bearing-grease-how-to-pack). Prices are on our [ball bearing grease comparison](/hub/diy-supplies/ball-bearing-grease), captured on 19 October 2026. A qualifying purchase can earn a commission at no extra cost to you.
A warm caravan wheel, or a boat trailer just out of the water, raises the same question.
A warm caravan wheel, or a boat trailer just out of the water, raises the same question. Trailer wheel bearing grease only belongs in a hub you can open, on the interval the hub maker prints, and kept off the brake linings. Peter F., editor for DIY supplies, sets out separate cones against unitised hubs, the grease Knott names, and what changes in the water. Hand-packing is on how to pack a wheel bearing with grease. Prices are on our ball bearing grease comparison, captured on 19 October 2026. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Stated bearing job | Grade on the listing | Extreme-pressure additive | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Carlube Carlube XMM500 Moly Grease 500 g | Machinery, anti-wear | NLGI 2 | Molybdenum disulphide | 8.0 | about £12.50 | View offer |
| Alternative |  Comma Comma GR2400 Multipurpose Lithium Grease 400 g | Wheel bearings, hubs, UJs | n/a | n/a | 8.2 | about £7.95 | View offer |
On this page
Two hub types
Separate taper-roller cones can be cleaned and packed. A unitised hub is a different part. The National Trailer and Towing Association says unitised hubs cannot be greased and are not waterproof. Knott says its unitised bearings are lubricated for life and are replaced, not refilled. Pumping one until grease appears is how a seal fails.
The practical test is the parts diagram for your axle, not the word bearing on a tub. If the service is a new cartridge and a new flange nut, you do not need a grease gun. If the service is cones, a seal, and fresh grease, you do. A small bike tube is not a trailer specification. Once you know the hub is unitised, stop.
The grease and the interval Knott prints
Knott's fitting sheet for separate bearings names Shell Retinax EP2, every 12 months or 12,000 miles, whichever comes first. Shell's data sheet for Gadus S2 V220 2 says that grease was formerly Retinax EP 2, with a range of −20 °C to +130 °C. If your hub is a Knott separate bearing, that is the name to buy. The 12-month line is Knott's line for those hubs, not for a unitised axle and not for every car wheel.
Comma GR2400 is a 400 g lithium tube at £7.95 that names wheel bearings. It does not print NLGI, a temperature, Retinax, or Gadus. Use it only where the hub maker has allowed a general lithium grease. Carlube XMM500 is a 500 g moly jar with NLGI 2 at £12.50. Texaco's UK moly EP2 is for CV joints, not high-speed rolling bearings. Moly for a sliding joint is a separate choice.
Boat trailers and salt water
Immersion changes the clock. The National Trailer and Towing Association says that if boat-trailer hubs are immersed, you should service them at least every three months. That is shorter than Knott's 12 months or 12,000 miles because water, not mileage, is the damage. The same page says not to dunk a hot hub. Cold water will be pulled past the seal as a hot hub cools. Let it cool in the air, then hose salt off the outside.
Unitised hubs do not become serviceable because they have been in the sea. If one rumbles after immersion, replace the unit. Open a serviceable hub on the calendar, not after the grease has turned milky.
Grease and the brakes
Grease on a lining or a drum face reduces braking. Knott's reason for an empty cavity is that excess grease walks outward and reaches that friction surface. A light coat on the race is the instruction. If you already see grease on the shoes, do not tow. Replace the shoes and the seal, then repack at the proper fill.
The NTTA brake-drum page gives example torques for named one-shot nuts: AL-KO 290 Nm, Ifor Williams 350 Nm, and Avonride 280 Nm. Those figures apply only to the nuts that page names. Book the axle if the wheel rumbles, if a race is pitted, or if you cannot set the torque your axle prints. A failed bearing can detach the wheel.
Common questions
What grease does Knott name?
For separate bearings, Knott names Shell Retinax EP2. Shell now sells that grease as Gadus S2 V220 2, stated at −20 °C to +130 °C. The interval on Knott's sheet is every 12 months or 12,000 miles. A multipurpose lithium cartridge that merely says wheel bearings is not that product unless the label says so. Unitised Knott bearings are lubricated for life and are not greased with it.
What changes if the trailer goes in the water?
Service immersed hubs at least every three months, hose salt off after you launch, and do not dunk a hot hub. Cooling metal can pull water past the seal. Unitised hubs are still not greased. They are not waterproof, and immersion does not create a nipple you should pump. If the brake needs stripping after salt water and you cannot keep the shoes clean, book the work.
Can a unitised hub be pumped full?
No. The NTTA says unitised hubs cannot be greased. Knott replaces them rather than refilling them. A grease gun on that hub pushes lubricant past a seal that was not a filling point, and the brake is the next surface in line. The service is a new unit and, where specified, a new one-shot flange nut. A 4.6-star cartridge does not change that design.
What are the one-shot nut torques for?
They are examples on the NTTA brake-drum page for named nuts: AL-KO 290 Nm, Ifor Williams 350 Nm, and Avonride 280 Nm. Use them only for those nuts. Your axle sheet wins if it prints a different figure. They are not a torque for every trailer in the UK, and they are not a reason to reuse a one-shot nut. Without a wrench that can set the stated torque, leave the nut to a workshop.
Is a multipurpose lithium cartridge the same as Retinax EP2?
No. Comma GR2400 is a 400 g lithium tube at £7.95 that names wheel bearings and does not state NLGI, temperature, Retinax, or Gadus. Reviewers use it on trailers. That is evidence of use, not evidence that it meets Knott's named grease. Buy Gadus S2 V220 2, or the current Shell name for Retinax EP2, when the hub sheet asks for that product.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Listings stored 19 October 2026.
- SKF: selecting a suitable grease (retrieved 19.10.2026)
- SKF: grease compatibility (retrieved 19.10.2026)
- NLGI Ask the Expert, Q4 2025 (retrieved 19.10.2026)
- NLGI: NLGI grade (retrieved 19.10.2026)
- HSE: SR19 lubricants and waste oil (retrieved 19.10.2026)
- HSE: GB CLP (retrieved 19.10.2026)
- Knott UK: hub fitting instructions (retrieved 19.10.2026)
- NTTA: boat trailers (retrieved 19.10.2026)
- Mobil: Mobilux EP 2 Moly (retrieved 19.10.2026)
- Texaco UK: Molytex EP 2 (retrieved 19.10.2026)
- Park Tool: HPG-1 (retrieved 19.10.2026)
- Shell: Gadus S2 V220 2 (retrieved 19.10.2026)