Description
Cortec® M-529 is a patented oil-based corrosion inhibitor package for lubricating oils in systems that run intermittently: gasoline and diesel engine oils, hydraulic lubrication and other process oils. Added at 2 to 5 % by weight it protects during operation and during the stops, and the equipment can keep running with it in the oil. The 5-gallon pail treats roughly 100 gallons of oil at the 5 % rate.
Standby engines, seasonal gearboxes and process pumps spend most of their life not turning, and that is when oil drains off the upper surfaces and condensation gets to work. M-529 is formulated for mineral oil and for naphthenic, iso-paraffinic and PAO synthetic base stocks, so it can be added to the oil already in the machine rather than replacing it. In the Cortec Product Consultation Guide M-529 and M-529 SC carry the additive mark, safe to use on all eight listed metals with application details from Cortec, meaning it is a fluid additive rather than a stand-alone coating and its protection follows the oil. Two grades sit beside the standard product: M-529 SC super concentrate at 1.5 to 3.5 % by weight, and M-529 L with an EP lubricity package for gears and transmissions.
Typical applications
- Lubricating oil systems in intermittent operation
- Mineral and synthetic oil formulations
- Gears and transmissions (M-529 L grade)
- Layup rust prevention
- Gasoline and diesel engine crankcases on standby generators and fire pumps
- Hydraulic lubrication and process system oils
- Gearboxes in mothballed power plants and process units
- Rebuilt gearboxes and transmissions filled before storage
How to apply M-529
- Choose the grade. M-529 for most lubricating oils; M-529 SC where a lower treat rate is wanted; M-529 L when the gearbox or transmission needs EP lubricity as well.
- Check compatibility. Cortec’s oil compatibility chart lists M-529 as compatible at 3 to 10 % in most mineral and PAO gear, turbine and hydraulic oils tested, and as not compatible with polyglycol (PAG) gear oils and certain synthetic compressor oils. Blend a sample of your oil first if it is not on the chart.
- Dose. Add 2 to 5 % by weight of M-529 (1.5 to 3.5 % for M-529 SC) to the sump or reservoir. Run the machine or circulate the oil until the additive is distributed.
- Operate or lay up. Equipment can operate normally with M-529 in the fluid. For lay-up, leave the treated oil in place or drain it; rotate or energize the equipment periodically if practical.
- Re-dose. Add M-529 again at each oil change or top-up to hold the treat rate.
- Storage. Keep sealed; shelf life up to 24 months.
Compatibility
Cortec’s oil compatibility chart lists M-529 as compatible at 5 % in a wide range of mineral and PAO gear and hydraulic oils, at 3 % in common turbine oils and at 10 % in several Mobil DTE and Mobil Gear grades, and as not compatible with polyglycol gear oils and certain synthetic compressor oils. On elastomers it is compatible at 10 % with Viton and PTFE and at 5 % with nitrile, subject to a Cortec consult. See the full oil and elastomer compatibility charts.
Where it fits in the Cortec line
M-529 is the engine-oil and process-oil inhibitor package. M-531 is the sibling for turbine, gear and hydraulic oils where demulsibility and a non-staining film are required and where fogging is wanted; M-535 is the ashless version for turbine, gear and compressor oils. The VpCI oil concentrates VpCI-322 and VpCI-329 add stronger vapor-phase protection for equipment that will be drained and stored, and are the choice when the oil is preservation oil rather than a working lubricant. Browse the full Cortec VpCI line.
Field notes
On a Gulf of Mexico rig mothballed in 2015, gearboxes were dosed with M-529, M-530 or M-531 according to compatibility tests with each unit’s oil while the exteriors went under MilCorr. The rig took a near-direct hurricane hit in 2017, and the 2019 inspection found nothing rusted. (Cortec Case History #662)
A Virginia gantry-crane gearbox rusty inside was restored without disassembly: filled with VpCI-422, soaked 20 minutes and rotated 5 minutes, three times; drained and filled with 1:1 VpCI-414 and water, rotated 30 minutes and drained; a borescope confirmed the rust was gone; then filled with oil plus M-531 and run 5 minutes at low speed. Two years of preservation. (Cortec Case History #828)
A French gear-reducer maker had precision reducers rusting in shipment, and filling the cases with oil was costly and shipped as hazardous freight. VpCI-329 is now poured into the gearcase at only 0.3% of case volume, with CorShield VpCI-369 on the exterior: up to 48 months of protection, no oil fill and non-hazardous freight. (Cortec Case History #599)
Specifications
| Dosage | 2–5% by weight in lubricating oils; M-529 SC superconcentrate 1.5–3.5% by weight |
|---|---|
| Base stocks | Mineral oil, and synthetic oils — naphthenic, iso-paraffinic and PAO |
| Applications | Lubricating oils for gasoline and diesel engines, hydraulic lubrication, process system oils |
| Operation | Equipment can operate with M-529 in the fluid; suitable for wet or dry lay-up |
| Humidity (ASTM D1748) | 480 hours on carbon steel |
| Flash point (ASTM D92) | 386 °F (197 °C) |
| Viscosity | 185 cSt at 40 °C; 16.5 cSt at 100 °C |
| Metals | Carbon steel, stainless steel, galvanized steel, aluminum, brass, copper, bronze |
| Grades | M-529 SC superconcentrate (1.5–3.5% by weight); M-529 L includes an EP lubricity package for gears or transmissions (3–6% by weight) |
| Test methods | MIL-PRF-46002 and MIL-PRF-85062 VCI oil; ASTM D665, D1748, D4172; M-529 L passes FZG load stage 12 (ASTM D5182) at 4.5% |
| Elastomers | Compatible at 10 % with Viton and PTFE; nitrile at 5 % (consult Cortec) |
| Shelf life | Up to 24 months sealed |
| Size | 5 Gallon Pail |
| Shipping weight | 41 lb (18.6 kg) |
| Availability | In stock |
| Cortec product number | 14503096 |
Solvent Recycling Systems is an authorized Cortec® distributor. See the full Cortec VpCI line, browse the VpCI product selection guide, or contact us for volume pricing and lead times.
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