Crane Gearbox Oil Type: Viscosity, Change Intervals & Mistakes

Quick answer: Most crane gearboxes use EP industrial gear oil in ISO VG 220 or 320 viscosity. The gearbox nameplate has the final word. Match the grade, never mix oil types, and change the oil after the running-in period, then by condition.

Need to pick the right crane gearbox oil type for your unit? The wrong oil films thin under load, cooks the seals, and scores the gear teeth. The right oil is one decision away: read the nameplate, match the viscosity, and follow the change rules below.

Why the Right Oil Type Matters

A crane gearbox runs under shock loads that ordinary oil cannot survive. Inside your gearbox, the oil does four jobs:

• It carries load. Extreme pressure (EP) additives form a film on the gear teeth that stops metal-to-metal scoring.
• It moves heat. Oil pulls friction heat away from the mesh and the bearings.
• It seals out contaminants. The oil film keeps dust and moisture away from the gear surfaces.
• It protects at start-up. The right viscosity flows fast on cold mornings, when most wear happens.

Choose the wrong type or grade, and the result is always the same: worn teeth, leaking seals, and a gearbox that fails long before its design life.

The Three Oil Types You Will Meet

Mineral EP gear oil

Standard closed gearboxes — most crane travel and hoist units — run on mineral-based EP gear oil, often marked CLP. It handles shock loads at the lowest cost. This is the default fill for most crane duty.

Synthetic gear oil

Synthetic oils hold their viscosity better at both temperature extremes and last longer between changes. Hot climates, cold sites, and high-duty gearboxes benefit most. You can run synthetic from new, but check your manual first: seals and ratings are designed around the specified oil.

Worm gear oil

Worm gearboxes are different machines. The sliding mesh between the worm and the wheel needs special oils with friction modifiers, not standard EP gear oil. Filling a worm unit with EP oil can actually increase wear. If your gearbox is a worm type, the oil spec on the plate is not optional.

Viscosity Grades: What ISO VG Means

ISO VG numbers describe oil thickness. A higher number means thicker oil. The grade decides how well the oil stays on the teeth at your working temperature.

Two warnings about this table. First, VG 220 and VG 320 are common grades, not your grade — the nameplate wins every time. Second, if your crane works across a wide temperature range, tell your supplier the site conditions, because the correct grade may change with them.

How to Choose the Correct Oil

Work through this order and you cannot go wrong:

1. Read the nameplate. It states the oil type and viscosity grade the gearbox was designed around.
2. Match the full specification. The manual lists the required EP level and ISO grade. Match the spec, not just a brand name.
3. Adjust for the site. Extreme cold or heat shifts the right grade. Your gearbox maker can confirm the alternative.
4. Fill to the level mark. Overfilling whips the oil into foam and overheats the unit.
5. Log the fill. Record the type, grade, quantity, and date on the gearbox or in your maintenance file.

When to Change Crane Gearbox Oil

Change intervals are not universal. They depend on duty class, load, temperature, and the oil itself. Use this sequence:

• First change: after the running-in period. New gears shed wear particles. Your manual defines this first interval, and it is shorter than any later one. Respect it.
• After that: follow the manual, then the condition. Check the level and look at the oil regularly. Dark color, a milky look from water, or metal glitter means change now, whatever the calendar says.
• After water ingress or overheating: change immediately. Contaminated oil keeps damaging gears until you drain it.

Condition beats calendar every time. A monthly two-minute oil check protects your gearbox better than a fixed schedule nobody inspects.

Gearbox Oil Mistakes That Cost You

• Topping up with a different type or brand. Additive packages can react and drop out. If an emergency top-up happens, plan a full change soon.
• Guessing the viscosity. Thicker is not better. Too thick starves bearings at start-up; too thin wipes off under load.
• Skipping the first change. The running-in oil change removes wear particles. Skip it, and they circulate through every bearing.
• Filling to the top. Oil needs room to work. Overfill causes foam, heat, and leaks.
• Reusing a worn plug seal. A leaking drain plug quietly drains the gearbox until the teeth run dry.

Wrong oil shows up later as noise, heat, and leaks. If your gearbox already runs loud, see how to reduce crane gearbox noise. For damage patterns beyond lubrication, read common crane gearbox problems and solutions. And if the unit itself is due for replacement, our guide to choosing the right crane gearbox covers sizing and duty class.

FAQ

Get the Right Gearbox and the Right Oil Data

The easiest oil decision is a gearbox with the data on the plate. Crane gearboxes from HANKO ship with clear lubrication specifications, so your team fills the right oil from day one. Full oil data sheets are available on request. Need OEM gear units or lubrication data for an existing unit? Contact HANKO engineers for a custom quote.