This guide explains what a modern machine lubricant is made of and how each part supports reliability in plant. It includes clear charts and product links to Sinopec Online.
Why lubrication matters in industry
A stable fluid film between moving parts prevents metal contact, lowers friction, removes heat, suspends particles, and shields against corrosion. The right fluid reduces energy use and supports uptime. The wrong fluid increases wear and risk. Select by duty, environment, and maker limits.
What a lubricant contains
Machine lubricants are blends. The base oil provides viscosity and film strength. The additive package delivers functions that the base oil alone cannot provide. In greases a thickener holds the oil in place. Balance is essential because some additives interact and materials such as copper alloys or certain seals need care.
Base oil
- Determines viscosity and film behaviour
- Sets low temperature flow and high temperature stability
- Can be mineral, synthetic, or a blend
Additive package
- Controls oxidation and sludge
- Provides anti wear and extreme pressure response
- Improves cleanliness, corrosion resistance, and air release
Base oils
Mineral base oils are refined from crude and grouped by chemistry and viscosity index classes. Synthetic base oils such as polyalphaolefins, esters, and polyalkylene glycols give a wider temperature range and often cleaner operation. Blends are common where a balance of properties is needed at sensible cost.
| Base oil type | Strengths | Points to watch | Typical uses |
|---|---|---|---|
| Mineral groups one to three | Good general performance and broad availability | Lower oxidation resistance at high temperature than many synthetics | Hydraulics, gear oil, general plant |
| Polyalphaolefin | Good low temperature flow and strong oxidative stability | Seal choice and price sensitivity | Compressors, gearboxes, circulation systems |
| Ester | Very good high temperature stability and detergency | Check compatibility with some elastomers and paints | High temperature chains and synthetic blends |
| Polyalkylene glycol | Low traction and good deposit control | Not always miscible with mineral oils and needs suitable seals | Worm gears and high slip contacts |
Additive families
Treat rate differs between a quiet hydraulic pump and a loaded gear tooth.
Oxidation control
Antioxidants slow chemical ageing that thickens oil and forms deposits.
Anti wear and extreme pressure
Reactive compounds form a protective film when contact stress and temperature rise.
Corrosion inhibition
Polar molecules protect metal surfaces during wet or idle periods.
Detergent and dispersant
Surface active species keep parts clean and hold fine particles for removal by filters.
Viscosity index improvement
Polymers reduce the change in viscosity with temperature across seasons.
Air and foam control
Agents speed air release so pumps do not cavitate and sensors remain stable.
Water management
Demulsifiers help water separate in sumps where dry operation is required.
Special functions
Metal deactivators and tackifiers for greases are used where needed.
Greases and thickener systems
Grease is oil held in a matrix by a thickener. The oil still provides the fluid film and the same additive logic applies. NLGI grade indicates hardness. Choose grade for feed method and speed. Water resistance and mechanical stability are central for wet duties.
Selection checklist
- Duty including load, speed, and shock history
- Temperature at start and at steady state
- Contamination risk from water, dust, or process media
- Required viscosity grade and base oil family
- Additive type and any limits from the maker
- Compatibility with seals, paints, and soft metals
- Change interval and filtration level
- Site rules for safety and environment
Common failure modes
| Observed issue | Likely causes | Action |
|---|---|---|
| Varnish and sticky valves | Oxidation and thermal stress with poor air release | Stronger antioxidant system, correct viscosity, improved air release, tighter breathers |
| Gear tooth pitting | Boundary contact and contamination | Appropriate extreme pressure package, correct viscosity, better filtration and seals |
| Bearing washout in wet zones | Weak water resistance or wrong NLGI grade | Grease with better water resistance and stability, review feed rate |
| Foam and cavitation noise | Air ingress and poor air release | Anti foam and air release control, review return line design and sump depth |
Oil analysis and condition monitoring
Routine analysis supports change decisions. For critical assets measure viscosity at set temperature, acid number trend, water, particle count, elemental wear metals, and any markers that reflect the state of key additives. Match intervals to hours and risk. Confirm alarms with repeat tests and inspection of strainers and filters.
Product mapping
Hydraulic systems ISO grades
Enclosed gears API GL
- Sinopec GL 5 80W90 Heavy Duty Automotive Gear Oil
- Sinopec GL 5 85W140 Heavy Duty Automotive Gear Oil
- Sinopec Gear Oil collection
Greased bearings and pins NLGI grades
- Sinopec NLGI 2 Extreme Pressure Lithium Grease
- Sinopec Multipurpose NLGI 2 Red Lithium Grease
- Sinopec Moly Lithium NLGI 2 Extreme Pressure Grease
- Sinopec Lithium Grease range
Air compressors
Charts and visuals
Quick answers
What sets the service life of a lubricant
Thermal load, contamination, and additive consumption. Good breathers, filtration, and suitable change points extend life.
Does a higher viscosity always protect better
No. Too thick at start can starve bearings and raise energy use. Select the grade that meets film needs at operating temperature and still pumps at start.
Can greases be mixed
Mixing can cause softening or separation. If a change is needed, purge the old product and verify compatibility between thickener systems.
Next steps
Use the selection checklist, confirm maker limits, and choose the correct grade from Sinopec Online.
