Photo: “A rock-drill end, East Pool Mine”, Rijksmuseum, via Wikimedia Commons (CC0). A historic rock drill, not a Castrol product.
Pneumatic rock drills earn their keep in some of the harshest conditions in South Africa: gold and platinum mines, the Mpumalanga coalfields, aggregate quarries, tunnelling and roadworks. A rock drill is a hammer driven by compressed air, and the only thing between its piston and cylinder is a thin film of oil carried in by the air. Get the oil wrong, or feed too little, and you’ll see it in worn pistons, scored cylinders, rusted valves and lost metres per shift.
Here’s how to choose and use Castrol Magna RD rock drill oils.
Always follow your drill maker’s recommendation. Castrol’s data sheet says “the correct grade should be selected against specific equipment and for local operating conditions”, and that most manufacturers publish selection charts in their handbooks.
What makes rock drill oil different?
A hydraulic or gear oil sits in a sump. Rock drill oil doesn’t. It’s dosed into the air line, carried through the drill as a fine film, and leaves with the exhaust. So it has to:
- Stick to the piston, cylinder and valve surfaces instead of being blown straight out.
- Seal the piston so the drill keeps its striking power.
- Fight rust, because compressed air carries moisture and a drill standing between shifts rusts from the inside.
- Cope with temperature, from a cold Highveld morning on surface to hot conditions underground.
Castrol Magna RD 150 and RD 320
Castrol describes the Magna RD range (previously Castrol Rock Drill Oils) as “selected mineral oils specially compounded with lubricity fortifiers, corrosions inhibitors and tackiness additives”. Applications: “Mining, quarrying, constructions, roadworks, tunneling and excavations.”
The data sheet lists these advantages:
- High film strength
- Reduced friction and wear
- “Provide a suitable seal between piston and cylinder”
- “Helps maintain maximum percussion efficiency” and operating speed
- “Preferentially adhere to metal surfaces and resist blow-off”
- Allows “operation in conditions of high or low temperatures”
Castrol says “Magna RD oils are recommended for the following well-known companies including Gardner-Denver, Atlas Copco and SIG”, and adds that the correct grade should be selected from your equipment’s own chart. That is a recommendation, not an approval.
Magna RD Compound: a different approach
Castrol Magna RD Compound (previously Patent RD Compound) isn’t a straight oil. It is “a water-in-oil emulsion specially formulated with anti-wear, anti-rust and extreme pressure additives”, with 41 % water by weight on the data sheet. Castrol makes it “to operate as an in-line air tool lubricant in all pneumatic rock drills operating on mines with moderate to severe operating conditions.”
From the data sheet:
- “Magna RD Compound is non-flammable, i.e ‘dieseling’ which occurs in rock drill machines is prevented.”
- “The product does not become atomized into a mist at the exhaust of the drill, thus reducing fire and health hazards.”
- “Composition of the product ensures cleaner operating conditions and operator comfort especially in confined spaces such as shaft sinking.”
- “The product resists water wash-off.”
- “More environmentally acceptable than conventional rock drill lubricants, due to its high water content and the absence of heavy hydrocarbons.”
Magna RD Compound comes in 20 L and 210 L packs. Because it is an emulsion, it behaves differently in a line oiler from a straight oil, so ask us whether it suits your set-up before you switch.
Magna RD selector table
| Product | Type (per PDS) | Viscosity | Pour point* | Typical use |
|---|---|---|---|---|
| Magna RD 150 | Mineral, tacky, corrosion-inhibited | ISO VG 150 | −15 °C | Where your drill chart calls for VG 150 |
| Magna RD 320 | Mineral, tacky, corrosion-inhibited | ISO VG 320 | −12 °C | Where your drill chart calls for VG 320 |
| Magna RD Compound | Water-in-oil emulsion, anti-wear / anti-rust / EP | 3,400–3,800 mPa·s (Brookfield, 23 °C) | not printed | In-line lubricant for pneumatic rock drills on mines, moderate to severe duty |
*Typical values from the Castrol PDS, not specifications. Packs: Magna RD 150 in 20 L and 210 L; Magna RD 320 in 210 L; Magna RD Compound in 20 L and 210 L.
RD 150 or RD 320?
Your drill maker’s chart comes first. As a general rule of thumb (not from the data sheet):
- The lighter grade (RD 150) flows more easily through the line oiler in cold conditions and reaches the working parts faster at start-up.
- The heavier grade (RD 320) holds a thicker film in hot conditions and under heavy loads, where a thin oil can be blown off too quickly.
- Air pressure and volume matter too. More air flow carries oil through faster. If the chart allows a range, heavier conditions generally point to the heavier grade.
Unsure, or running mixed drill makes? Talk to us before you standardise on one grade.
Practical tips from the field
- Set the line oiler properly. Too little oil means dry running and fast wear. Too much wastes oil, fouls the work area and can stall the drill. Set it to the drill maker’s instructions. A quick check: a light, even film on the shank and at the exhaust, not dripping oil and not bone-dry metal. Check it’s feeding at the start of every shift.
- Keep the air dry. Drain the receiver, line water traps and separators daily, and more often in the rainy season. Fit a water separator ahead of the line oiler, and blow out the hose before connecting the drill.
- Keep it clean. Wipe couplings, cap unused hoses and use clean containers to fill lubricators. Grit in rock drill oil acts like grinding paste.
- Store it right. Keep drums under cover. If they must stand outside, lay them on their side so water can’t collect on the lid, and keep them out of hot sun. Use the oldest stock first.
- Don’t swap products without checking. Moving between a straight rock drill oil and an emulsion like RD Compound changes how the lubricator and drill behave.
Oil analysis and on-site checks from AVDMM
AVDMM offers oil analysis and on-site checks for our customers. We can look at your line oilers, water traps and oil condition on site, and help you read oil analysis results for the compressors that feed your drills. Ask us to set it up.
Underground use
Underground lubricant rules are set by your mine’s own standards and the regulations that apply. Castrol’s data sheet for Magna RD Compound says it is non-flammable and does not mist at the drill exhaust, “thus reducing fire and health hazards”. For any regulatory or site-approval question, check with your mine’s engineering and safety department, and read the Safety Data Sheet before use.
Running the compressors as well? See our guide to Castrol Aircol compressor oils.
Frequently asked questions
What is Castrol Magna RD?
Magna RD 150 and RD 320 are rock drill oils made from selected mineral oils compounded with lubricity fortifiers, corrosion inhibitors and tackiness additives, for mining, quarrying, construction, roadworks, tunnelling and excavation.
Magna RD 150 or RD 320: which do I need?
Use the grade on your drill maker’s selection chart. As a rule of thumb, the lighter RD 150 suits colder conditions and the heavier RD 320 suits hot conditions and heavy loads.
Is Magna RD approved by Atlas Copco, Gardner-Denver or SIG?
The PDS says Magna RD oils are recommended for well-known companies including Gardner-Denver, Atlas Copco and SIG. It does not state an approval. Always check your drill’s own chart.
What is Magna RD Compound?
A water-in-oil emulsion with anti-wear, anti-rust and extreme pressure additives, for use as an in-line lubricant in pneumatic rock drills on mines. The PDS says it is non-flammable and does not become atomized into a mist at the drill exhaust. It comes in 20 L and 210 L packs.
Can I mix Magna RD Compound with straight rock drill oil?
Get advice first. Moving between a straight oil and an emulsion changes how the lubricator and drill behave. Ask us whether RD Compound suits your set-up before you switch.
Does AVDMM check line oilers on site?
Yes. AVDMM offers on-site checks and oil analysis for customers. Contact us to set it up.
Talk to us about Magna RD
Castrol is sold by AVDMM Lubes (Level 2 B-BBEE). See our Castrol range and the other brands we supply.
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Based on Castrol product data sheets: Magna RD Range (25 Sep 2023; same text and figures as the Castrol South Africa issue of 29 Mar 2018) and Magna RD Compound (16 Oct 2018). Typical values are not specifications. This is general guidance; always follow your equipment manufacturer’s recommendations.