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 55-gallon drum is the size for a fleet of standby engines or a plant lube program.
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 | 55 Gallon Drum |
| Shipping weight | 459 lb (208 kg) |
| Availability | In stock |
| Cortec product number | 14503097 |
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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