Lubricants for aerial platforms and machines: oil types, changes, mixing and contamination

In short: always use the oil given in the machine's manual, keep it clean and change it at the manufacturer's intervals. Do not mix oils of different brands or types, because their additives can react with each other. If the oil looks milky, contains metal particles or rubber debris, or smells of fuel, stop the machine, find the cause and, in most cases, drain and flush the system and refill with new oil.

Almost all aerial work platforms and many construction machines rely on hydraulics. The clearances inside pumps, valves and hydraulic motors are so small that a little dirt is enough to wear them or make them stick. JLG points out that the human eye can only see particles of about 40 microns and above, and that contaminated oil can even void the warranty. Choosing, storing and changing lubricants properly is one of the cheapest ways to avoid breakdowns.

What lubricants does a machine use

Each model has its own oil. In a service manual for its ES electric scissor lifts, JLG recommends a 10W-30 multigrade hydraulic oil with a viscosity index of 152. In the manual for the 10MSP mast platform it specifies ISO VG 32 or 46 hydraulic oil and an extreme-pressure multipurpose grease with good water resistance. Before topping up, check the sticker on the tank and the manual.

Why oil quality and oil changes matter so much

Oil does four jobs at once: it transmits power, lubricates, cools and protects against corrosion. Over time, heat and water oxidise it, the additives are used up and particles build up. Tired oil still looks like oil, but it no longer protects as it should.

Intervals depend on the model and the work:

• In the ES scissor lift service manual, JLG recommends changing the hydraulic oil every year and replacing the filters once a year too.
• The 10MSP manual says to change the hydraulic oil every 2 years and check the level every day.
• For low-level access platforms, JLG says to replace the hydraulic oil at the annual inspection and check the system for contamination.
• The lubrication intervals in the manuals assume normal use. With heavy dust, humidity, salt or long working hours they should be shortened.

These examples are only indicative. The rule is always the maintenance schedule in your machine's manual, and oil analysis helps you decide when to change.

Why oils should not be mixed

Two oils with the same viscosity are not necessarily compatible. Every oil has an additive package (anti-wear, antioxidant, anti-corrosion, anti-foam, demulsifier), and different packages can react with each other. In its manuals JLG warns that mixing oils of different brands or types is not advisable and that petroleum and synthetic base oils should not be mixed.

What can happen:

• Precipitates and sludge: acidic additives in one oil react with basic additives in another, especially with water and heat, and form a paste that clogs filters and valves.
• Zinc and zinc-free oils: these two anti-wear additive systems are often incompatible.
• Foam and poor air and water release: the pump cavitates and the oil oxidises faster.
• Seals: some mixtures make seals swell or shrink, and leaks appear.
• Mineral with biodegradable: the mixture loses its environmental properties and its viscosity changes.

In a test cited by the European technical magazine Lube-Tech, more than a quarter of over 50 miscible hydraulic oils tested were not compatible. Even oils from the same brand may not be.

Look at the oil type too, not just the viscosity. Some manufacturers specify a multipurpose UTTO-type fluid, the kind used in tractor transmissions, for the hydraulic circuit rather than a standard "hydraulic" oil. In that case, topping up with a generic hydraulic oil of the same viscosity is still a mix. Check the manual or the label on the tank.

In practice: always top up with the same oil that is already in the machine. If you do not know which it is, do not take the risk: check with the oil supplier, from whom you can request a compatibility analysis.

How to change oil type

1. Confirm in the manual or with the manufacturer that the new oil is approved for the machine and its seals.
2. With the oil warm and the machine stowed, drain the tank and, if the manual says so, the cylinders, hoses and components.
3. Clean the tank and replace the filters.
4. Fill with the new oil, run every function and repeat the drain if needed.
5. Over the following weeks, keep an eye on the filters and request an oil analysis from the lubricant supplier.

When switching from mineral to biodegradable oil, the reference is ISO 15380, which allows at most 2% residual mineral oil. According to Q8Oils, about 40% of the old oil stays in the pumps, lines and cylinders after draining, so four drain-and-fill cycles may be needed, or fewer if the components are emptied.

Contamination: how to recognise it and what to do

For JLG, contamination is the main enemy of the hydraulic system: the wrong oil, moisture, grease, metal filings, seal debris or sand getting in during maintenance, or pump cavitation from too little warm-up or a suction leak. Every time you change filters, examine them for particles. If you find metal or rubber, JLG says to drain and flush the entire system.

Colour is a clue: a dark deposit suggests oxidation, milky oil suggests water, and a clear, oil-coloured gel or sludge mostly suggests mixed oils or additive precipitation. This sludge tends to settle in narrow passages, small valves and orifices, often far from the tank. So changing only the tank oil may not be enough, and several oil changes or system flushes may be needed.

On machines with electronic levelling or controls, a slow hydraulic response can trigger fault codes. So read the fault codes too: the same complaint can have a hydraulic or an electrical cause.

Oil analysis

A lab analysis shows what you cannot see: wear metals, water, fuel, glycol, dirt and the condition of the oil itself. You can request it from your oil supplier: lubricant suppliers and manufacturers offer analysis services. For the sample to be useful:

• Take it with the machine running, or always at the same time after shutdown, with the oil at working temperature, and always from the same point.
• Use clean sample bottles made for analysis and do not draw sediment or water from the bottom of the tank.
• Record the machine, its hours, the oil type and the hours since the last change.
• Compare with earlier results: the trend tells you more than a single value.

The ISO 4406 code

The ISO 4406 code has three numbers, for particles larger than 4, 6 and 14 microns per millilitre of oil. The lower the code, the cleaner the oil. JLG considers a code of 19/17/14 or lower acceptable. Above that, it calls for cleaning the system and changing the filters.

When to stop the machine

Stop the machine and call a technician if:

• you find metal filings or flakes in the filter, on the magnet or on the drain plug, outside the wear-in period of a new machine;
• the oil is milky or there is water at the bottom of the tank;
• the engine oil level rises on its own or smells of diesel;
• the analysis shows glycol, or coolant disappears with no visible leak;
• the pump is noisy, functions become slow or jerky, or the oil runs hotter than usual.

Carrying on spreads the dirt through the whole circuit and can turn a simple repair into a new pump, motor or cylinders.

Day-to-day good practice

• Clean storage: keep new oil under cover with drums tightly closed, and use funnels and containers dedicated to oil and labelled by type.
• Filtered top-ups: clean around the cap before opening it and, if you can, top up with a filtered pump.
• Filters and breathers: change filters at the intervals in the manual or when the clogging indicator warns you, and use genuine filters. Clean around the filter before opening it. Every time you change the oil, change the filter and clean the magnet. Check the tank breather filter.
• Cap everything: when you disconnect lines or components, cap the openings and keep new filters in their packaging until fitting.
• Washing: do not aim the pressure washer at breathers, caps or cylinder rods.
• Records: log every top-up and oil change in the machine's file, with the oil type used.

What to do with used oil in Portugal

Used oil is hazardous waste, and whoever produces it is responsible for sending it on, under Decree-Law 152-D/2017. According to the good-practice manual from Sogilub, the managing entity of Portugal's integrated used-oil management system (SIGOU), companies must:

• register on SIRER, in SILiAmb, and join SIGOU;
• hand used oil to a licensed waste operator in the SIGOU network;
• fill in the electronic waste transport forms (e-GAR).

Private individuals can take oil to Sogilub's "Do-It-Yourself" network.

Do not mix used oil with diesel, petrol, water, solvents, antifreeze or other products. If the oil does not meet the specifications, the cost of handling it can be charged to the producer. Store it in sealed, labelled containers over a drip tray. Oily filters and rags are not part of this circuit and must go to a licensed waste operator.

How Trapézio de Prismas can help

We are JLG's official dealer in Portugal. If you notice any of the signs described in this guide, or want to confirm your machine's condition before putting it back to work, request a technical inspection from Trapézio de Prismas.

You can also find filters and parts and the JLG manuals. For any questions, contact us.