AMSOIL ISO 46 100% Synthetic Compressor Oil
AMSOIL ISO 46 100% Synthetic Compressor Oil (PCI) is a long-life, ashless premium lubricant in the most common shop and industrial viscosity for rotary screw, vane, centrifugal, and reciprocating air compressors. The PC Series formulation pairs thermally stable synthetic base oils with non-detergent additives to hold viscosity, keep heads clean, and shed water.
Long-life service in rotary screw compressors
Drain intervals of up to 8,000 hours are achievable in rotary screw compressors operating under normal conditions at a 200 degree F discharge temperature. That service life cuts annual oil changes, planned downtime, and waste-oil disposal volume versus shorter-interval petroleum oils. Actual interval depends on temperature, load, intake air quality, and filtration, so periodic oil analysis is recommended on production-critical machines.
Superior varnish resistance verified by ASTM D7843
Varnish is the dominant failure mode in hot rotary screw compressors, building on rotors, bearings, separator elements, and control valves until efficiency drops and shutdowns follow. AMSOIL PC Series and a leading competitor synthetic compressor oil were run side by side in industrial rotary screw compressors at a 200 degree F oil discharge temperature and rated by the Membrane Patch Colorimetry Test (ASTM D7843). The competing oil reached critical varnish potential at 6,228 hours of service. AMSOIL PC Series ISO 46 (PCI) still showed ultra-low varnish potential at 8,000 hours.
Reduced top-off oil consumption
Excessive top-off wastes oil, time, and labor on every PM cycle. In an 8,000-hour side-by-side test in an industrial rotary screw compressor under matched operating conditions, the foam control and air-release properties of PC Series cut oil consumption 35 percent versus a leading competitor synthetic ISO 46 compressor oil.
Water separation and rust protection
Condensation is unavoidable in compressed air systems, and trapped water drives rust, corrosion, and emulsions that strip lubrication from sliding contacts. PC Series ISO 46 is hydrolytically stable, anti-rust fortified, and engineered to release water rapidly through the bottom of the sump. Rust performance is verified by ASTM D665 A and B in fresh and synthetic sea water, and demulsibility (ASTM D1401) returns a 40/40/0 split with cuff break in 10 minutes.
Wear control and clean operation
The non-detergent chemistry drops contaminants out of suspension into the sump rather than circulating them through the system, matching how compressor sumps and separators are designed to handle dirt. Anti-wear additives protect bearings, gears, and slide valves, and the Four-Ball Wear Test (ASTM D4172) returns a 0.42 mm scar at 40 kg, 1,200 rpm, and 75 degree C. Copper strip corrosion (ASTM D130) is rated 1A.
Improved fire safety margin
The PC Series chemistry is ashless, with a high flash point and very low carbon-forming tendencies that limit ignition-promoting hot spots inside hot compressor stages. ASTM D92 puts the ISO 46 grade at a 260 degree C / 500 degree F flash point and a 288 degree C / 550 degree F fire point. The product improves the fire-safety margin of a compressor lubrication system but is not a fire-resistant fluid.
Recommended applications and service intervals
AMSOIL ISO 46 100% Synthetic Compressor Oil (PCI) is the all-purpose viscosity for typical shop and industrial air compressors and pump applications running at moderate temperatures. The same oil covers rotary screw heads, rotary vane pumps, centrifugal compressors, and the crankcases and cylinders of reciprocating units, as well as vacuum pumps, pressure washer pumps, gears, bearings, and blowers calling for an ISO VG 46 lubricant. Confirm grade and capacity for any specific machine in the equipment maintenance manual or the compressor oil guide.
- Rotary screw compressors: drain intervals up to 8,000 hours under normal operation at 200 degree F discharge, subject to oil analysis.
- Reciprocating, vane, and centrifugal compressors, vacuum pumps, and pressure washer pumps: service per the equipment manufacturer schedule, with oil analysis on critical units.
- Not recommended for breathing air compressors or refrigeration compressors.
- Not for use with polycarbonate or PVC plastics, or with butyl, ethylene-propylene, or SBR rubber. Not compatible with polyalkylene glycol or silicone oils.
For best performance, drain the existing oil, follow the manufacturer procedure to remove any carbon or varnish deposits from internal components, and change the air and oil separator filters before charging with PCI. The formulation is compatible with petroleum oils and most other synthetics, but topping a contaminated sump shortens drain interval and is not a substitute for a proper changeout.
Typical technical properties
| Property | Value |
|---|
| ISO Viscosity Grade (ASTM D2422) | 46 |
| SAE Viscosity Grade | 20 |
| Kinematic Viscosity at 100 degree C, cSt (ASTM D445) | 7.3 |
| Kinematic Viscosity at 40 degree C, cSt (ASTM D445) | 43.0 |
| Viscosity Index (ASTM D2270) | 132 |
| Specific Gravity (ASTM D1298) | 0.8529 |
| Density, lbs/gal (ASTM D1298) | 7.1 |
| Flash Point, degree C (degree F) (ASTM D92) | 260 (500) |
| Fire Point, degree C (degree F) (ASTM D92) | 288 (550) |
| Pour Point, degree C (degree F) (ASTM D97) | -38 (-36) |
| Four-Ball Wear Test, mm (ASTM D4172, 40 kg, 1,200 rpm, 75 degree C, 1 hr) | 0.42 |
| Copper Strip Corrosion (ASTM D130) | 1A |
| Rust Test, fresh and synthetic sea water (ASTM D665 A and B) | Pass |
| Foam, Sequence I, II, III (ASTM D892) | 0/0, 10/0, 0/0 |
| Demulsibility, oil/water/cuff, minutes (ASTM D1401) | 40/40/0 (10) |
Order AMSOIL ISO 46 100% Synthetic Compressor Oil
Available sizes include the quart bottle (PCIQT-EA), case of 12 quarts (PCIQT-CA), 5 gallon pail (PCI05-EA), and 55 gallon drum (PCI55-EA). Every PC Series purchase is backed by the AMSOIL Limited Liability Warranty for lubricants. To match this oil to a specific compressor make, model, and stage configuration, see the compressor oil guide and the vehicle and equipment lookup guide, then place the order through AMSOIL ISO 46 100% Synthetic Compressor Oil.
Customer reviews
Reasonably priced synthetic compressor oil
As advertised. The only down side is that they don’t sell on Amazon or provide free shipping.
By Brent from Florida on February 22, 2026.
Would recommend this to a friend.
Compressor oil
Good stuff never had a problem
By Brian from Tennessee on December 29, 2025.
Would recommend this to a friend.
Use in my Tuthill Blower
Been using this for years to maintain my blower, I won't use anything else
By Tim from TX on November 27, 2025.
Would recommend this to a friend.
Read all 57 reviews
Frequently asked questions
Can synthetic motor oil be used in an air compressor instead of compressor oil?
No. Passenger car and diesel engine oils carry detergent and dispersant chemistry tuned for combustion byproducts, not for the moisture, varnish, and air-release demands of a compressor sump. AMSOIL ISO 46 100% Synthetic Compressor Oil is a non-detergent, ashless formula engineered specifically for rotary screw, vane, centrifugal, and reciprocating compressor service.
What viscosity is ISO 46 compressor oil?
ISO VG 46 (ASTM D2422) corresponds to 43.0 cSt at 40 degree C and 7.3 cSt at 100 degree C, equivalent to an SAE 20 weight. PCI is the most common shop and industrial grade for general-duty rotary screw and reciprocating compressors at moderate temperatures, plus vacuum pumps and pressure washer pumps that call for an ISO 46 fluid.
How often should the oil be changed in a rotary screw compressor?
Drain intervals of up to 8,000 hours are supported in rotary screw compressors at a 200 degree F discharge temperature under normal conditions. Higher discharge temperatures, heavy duty cycles, dusty intake air, or wet environments shorten the interval. Periodic oil analysis is the most reliable way to set the actual change point.
What is the difference between detergent and non-detergent compressor oil?
Detergent oils hold combustion soot and varnish precursors in suspension so the filter can capture them, which suits engines but loads the air-oil separator in a compressor. Non-detergent compressor oils, including PC Series, let contaminants drop out in the sump where the drain plug removes them, keeping varnish and sludge off rotors, bearings, and separator media.
Will this oil resist water contamination from compressor condensate?
Yes. PC Series ISO 46 is hydrolytically stable and anti-rust fortified, and the demulsibility result (ASTM D1401) shows a clean 40/40/0 oil and water split with cuff break in 10 minutes. The oil separates from condensate quickly so water can be drained from the sump rather than carried through the system as an emulsion that strips the lubricant film.
Is this oil suitable for breathing air or refrigeration compressors?
No. AMSOIL ISO 46 100% Synthetic Compressor Oil is not recommended for breathing air or refrigeration compressors, and it is not compatible with polycarbonate or PVC plastics, butyl, ethylene-propylene, or SBR rubber, or with polyalkylene glycol or silicone oils.
Can PCI be mixed with the existing oil during a top-off?
The PC Series formulation is compatible with petroleum oils and most other synthetic compressor oils, so a small emergency top-off will not damage the system. The full 8,000-hour service capability requires draining the prior oil, removing carbon and varnish deposits per the compressor manufacturer procedure, and replacing the oil and air-oil separator filters before charging with PCI.
