Lubricant Additive Packages
CheMost supplies gear oil additive packages — extreme-pressure (EP) concentrates a blender adds to base oil to make a finished gear or transmission oil, spanning automotive axles and transmissions, industrial enclosed gearboxes, and bronze-wheel worm drives.
These are additive components for finished-lubricant formulators — not a finished gear oil and not a consumer gear additive. A gear oil is not chosen by viscosity alone, nor by “more EP is better”: the package is set by the gear’s type and metallurgy, because the same EP chemistry that protects a hypoid axle can attack the yellow metals in a synchronized gearbox or worm drive. Choose by hardware below, then request the data sheet.
The Selection Principle: Match the EP to the Gear — Not “More Is Better”
This is the part the thin “75W-90” listings skip, and it is where the choice is actually made. The right gear package is set by the gear hardware and the metals it is made of:
- Automotive or industrial — do not cross them. Automotive axles and manual transmissions run to API GL-4/GL-5/MT-1; industrial enclosed gearboxes run to AGMA 9005 and ISO 12925-1 (CKC/CKD), where fast water separation and micropitting resistance matter as much as EP. An automotive gear oil dropped into an industrial gearbox carries chemistry that gearbox does not need — and may not want.
- GL-4 vs GL-5 is the critical fork, and the yellow metal is the limit. GL-5 carries roughly double the active sulfur–phosphorus EP for high-load hypoid axles — but that same aggressive EP can attack the yellow-metal (brass/bronze) synchronizers in some manual transmissions. A synchronized manual usually needs GL-4 (or a yellow-metal-safe GL-4/5), not GL-5. As the standards bodies put it, a 75W-90 is a viscosity, not a performance level, and GL-5 is not automatically right for every gearbox.
- Worm gears mean a bronze wheel — so mild, compatible EP. A worm-and-wheel drive has a bronze wheel that a hypoid-grade EP oil corrodes. It needs a bronze-compatible, mild-EP / compounded package (PA4400M), not a GL-5.
- Industrial gearboxes need more than EP. Enclosed industrial drives demand fast water separation (demulsibility), micropitting and scuffing resistance (the FZG test) and long oxidation life, on top of load-carrying EP.
So the decision order is: automotive vs industrial → GL-4 vs GL-5 + yellow metal → worm (bronze) → industrial AGMA/ISO + FZG + water → viscosity. The three packages below put that into practice.
What a Gear Package Does
Gear teeth meet under far higher contact pressure than engine or hydraulic surfaces — a hypoid mesh can reach several GPa — so the package must carry load without attacking the gear metals:
- Extreme-pressure & anti-wear. Sulfur-carrier and phosphorus chemistry builds a sacrificial film that protects the tooth flank under high sliding and shock load.
- Yellow-metal compatibility, balanced against EP. The EP system is balanced — and, for worm and synchronized drives, deliberately milder — so it protects steel without corroding bronze and brass.
- Oxidation & thermal stability. Antioxidants resist sludge and viscosity rise at high sump temperatures for long drain life.
- Rust, demulsibility & foam control. Rust inhibitors and demulsifiers protect ferrous parts and shed water — critical for industrial gearboxes exposed to moisture.
The CheMost Range — Choose by Gear Hardware
Three packages across automotive, industrial and worm-gear duty. Open a grade to request its data sheet.
PA4001 — Versatile (automotive + industrial)
For: ISO CKC/CKD + API GL-4/GL-5.
Best for: Blenders who want one package to cover a broad line — formulated to meet ISO CKC/CKD industrial and API GL-4/GL-5 automotive requirements at the appropriate treat rate. Mineral and Group II base oils.
Request TDS & Sample →PA4001S — High-performance
For: More demanding duty.
Best for: The higher-performance grade in the range, for more demanding automotive and industrial gear duty. Confirm the performance tier and targets from its data sheet.
Request TDS & Sample →PA4400M — Worm gear (bronze-compatible)
For: Worm-and-wheel drives.
Best for: Enclosed worm reducers with a bronze wheel — a bronze-compatible, mild-EP chemistry formulated to carry the sliding load while remaining compatible with the bronze wheel, with oxidation and rust protection. Confirm targets from its data sheet.
Request TDS & Sample →Specifications — All Grades data on request
The concentrate fingerprint for each grade — the EP elements (sulfur and phosphorus), nitrogen, viscosity and copper-corrosion behaviour — published per grade as test data is confirmed. Request the current data sheet for any grade.
| Property | Method | PA4001 | PA4001S | PA4400M |
|---|---|---|---|---|
| Appearance | Visual | — | — | — |
| Kinematic viscosity @100 °C, mm²/s | ASTM D445 | — | — | — |
| Flash point (COC), °C | ASTM D92 | — | — | — |
| Sulfur, wt% | ASTM D4951 | — | — | — |
| Phosphorus, wt% | ASTM D4951 | — | — | — |
| Nitrogen, wt% | ASTM D5291 | — | — | — |
| Copper corrosion | ASTM D130 | — | — | — |
Properties are reported as concentrate (package) values to the ASTM methods shown, not finished-oil values; published per grade as test data is confirmed. Request the current TDS for any grade.
Performance Coverage
Formulated to meet the requirements of
Coverage differs by grade: PA4001 and PA4001S are the automotive (GL-4/GL-5) and industrial (CKC/CKD, AGMA) grades; PA4400M is a dedicated bronze-compatible worm-gear package — deliberately mild-EP, and not a GL-5 hypoid oil. These are formulation targets per grade against the public API, ISO and AGMA categories, at the appropriate treat rate in a suitable base oil — not licenses or qualifications. The SAE J2360 qualification and any OEM gearbox approval are held by the finished-oil marketer who tests and qualifies the finished oil, not by the additive package. Read load capacity with the FZG scuffing and 4-ball EP tests, and yellow-metal behaviour with copper-strip corrosion — the package contributes, but the finished oil is what is qualified.
The Gear Standards Map
- Automotive — API 1560 (GL-4 / GL-5 / MT-1). GL-4 for spiral-bevel and many synchronized manuals; GL-5 for high-load hypoid axles; MT-1 for non-synchronized heavy-duty manuals. SAE J2360 is the global framework that integrates GL-5 + MT-1 requirements.
- Viscosity — SAE J306. The 75W-90 / 80W-140 grades are a viscosity window, separate from the performance level.
- Industrial — AGMA 9005 & ISO 12925-1 (family C: CKC/CKD). Enclosed-gear classifications that add water separation, micropitting and FZG scuffing to the EP requirement. Universal and dedicated industrial oils are not interchangeable.
Common Applications
- Automotive axles & differentials (GL-5): hypoid rear axles in cars, trucks and SUVs — PA4001 or PA4001S at GL-5 treat rate.
- Manual transmissions (GL-4): synchronized gearboxes needing yellow-metal-safe EP — PA4001 at GL-4 treat rate.
- Industrial enclosed gearboxes (ISO CKC/CKD, AGMA): circulating and splash-lubricated industrial drives — PA4001 or PA4001S at industrial treat rate.
- Worm-gear reducers: enclosed worm drives where bronze-wheel compatibility is mandatory — PA4400M.
- Open gears & mill drives: compounded gear oils pairing a gear package with a tackifier — ask CheMost for a starting formulation.
Need help choosing a gear package?
Tell us the gear type (hypoid axle, synchronized manual, worm drive or industrial gearbox), the target API / ISO / AGMA grade, any yellow-metal constraint and the viscosity grade. We will point you to the right package and a starting treat rate, then share the relevant technical documents. Samples in 1 kg and 5 kg; bulk in 200 kg drums and 1000 kg IBC, with COA, TDS and SDS per shipment.
Request a Sample Get a QuoteA finished gear oil is built from an extreme-pressure / anti-wear system, antioxidants, rust inhibitors, yellow-metal passivators and demulsifiers; open-gear compounds add a tackifier. See the additive packages overview, and Automotive and Industrial Lubricant applications.
Quick Reference
What is the difference between API GL-4 and GL-5?
GL-5 calls for higher extreme-pressure performance than GL-4 for high-load hypoid gears, and typically carries roughly double the active sulfur–phosphorus EP chemistry. It is not simply a “higher” GL-4, though — its more aggressive EP is not automatically suitable for synchronized or yellow-metal gearboxes (see below). PA4001 is formulated to either grade by adjusting the treat rate; request the respective TDS.
Can a GL-5 gear oil be used in a manual transmission?
Caution is required. The aggressive EP chemistry in a GL-5 oil can attack the yellow-metal synchronizer components in some manual transmissions, so a GL-4 (or a yellow-metal-safe GL-4/5) is usually specified there. Always verify the OEM requirement; PA4001 at GL-4 treat rate is the safer choice for most synchronized transmissions.
Why does a worm gear need a special package?
Worm-and-wheel drives use a bronze wheel that is sensitive to sulfur-based EP additives — a standard GL-5 chemistry can corrode the bronze over time. PA4400M uses a milder, metal-compatible chemistry that protects against wear without chemically attacking the non-ferrous wheel.
Is 75W-90 a performance level?
No. 75W-90 (and 80W-140, etc.) is a SAE J306 viscosity grade — it describes flow, not performance. The performance level is the separate API (GL-4/GL-5/MT-1) or ISO/AGMA designation, and a GL-5 is not automatically suitable for every gearbox.
Can I use an automotive gear oil in an industrial gearbox?
Not as a rule. Industrial enclosed gearboxes need fast water separation, micropitting resistance and long oxidation life; some components of a universal automotive gear oil are unnecessary — or unhelpful — there. Use a package formulated to the industrial AGMA / ISO 12925-1 requirement (PA4001 or PA4001S at industrial treat rate).
What else do I need to make a finished gear oil?
Base oil of the right group and viscosity (SAE J306 for automotive, ISO VG for industrial), this package at the targeted treat rate, and — for open-gear compounds — a tackifier. CheMost can advise the full formulation and a starting point.
About this page & our data. The specifications and test methods on this page are public references (API, ACEA, DIN, ISO, SAE) — not CheMost measurements. Grade specifications come from each package’s TDS; where a value is not confirmed for a grade, we mark it “on request” rather than estimate. CheMost is a manufacturer and sourcing partner established in 2013; OEM and API/ACEA licences are held by the finished-oil marketer, not the additive package. Last reviewed June 2026 · CheMost technical team.
Explore Other Additive Packages
Every CheMost ready-to-blend package, at a glance. Match the finished-oil specification you are building — open any family to see grades, performance tiers, and treat rates.