AMSOIL NLGI #1 Synthetic Polymeric Truck, Chassis, and Equipment Grease
AMSOIL NLGI #1 Synthetic Polymeric Truck, Chassis, and Equipment Grease (GPTR1) is a softer-consistency, calcium-sulfonate-complex chassis grease engineered for heavy-duty over-the-road trucks, trailers, and severe-service equipment. The NLGI #1 grade pumps cleanly down to colder temperatures than its NLGI #2 counterpart, making GPTR1 the right pick for fleets running through winter or operators who hand-grease chassis points in cold weather.
Calcium-sulfonate complex thickener with proprietary polymeric chemistry
The formula combines synthetic base oils with a calcium-sulfonate complex thickener and a proprietary polymeric additive system. Calcium-sulfonate complex thickeners give the grease inherent rust and corrosion protection, high dropping point and excellent water tolerance without relying on supplemental anti-wear chemistry to do the same job. The polymeric component contributes the tacky, stringy texture that helps the grease stay welded to metal under shock loads and high-pressure rolling contact.
Extreme-pressure and shock-load protection
Wheel bearings, fifth-wheel plates, kingpins and U-joints on Class 6-8 equipment regularly see shock loading and high-contact-pressure conditions. GPTR1 carries a Timken OK Load of 65 lbs. (ASTM D2509) and a Four-Ball Weld Point of 620 kgf (ASTM D2596), placing it in the top tier of chassis greases for extreme-pressure capability. The polymeric chemistry adds film toughness, so the lubricant resists pounding out of joints under repeated impact.
Stays in place, seals out water
The same tacky structure that resists pounding also keeps the grease anchored on chassis components exposed to spray, slush, and road salt. Water washout (ASTM D1264) measures 7%, and the formula passes the ASTM D1743 rust-prevention bearing test. That combination helps fifth-wheel plates, spring pins and steering linkages shed contamination instead of absorbing it, which is what drives premature corrosion-related wear on linehaul equipment.
High-temperature stability with cold-weather pumpability
Dropping point (ASTM D2265) is 260 °C (500 °F), giving GPTR1 a wide operating ceiling for heavily loaded wheel bearings and high-speed components. At the cold end, the NLGI #1 consistency and 68 cSt base oil viscosity at 40 °C (ASTM D445) deliver the pumpability the GPTR2 grade cannot match. GPTR1 pumps best in temperatures above 0 °F. The NLGI #2 version (GPTR2) pumps best above 40 °F, so operators in northern fleets, mountain routes and winter service generally land on the #1 grade for centralized hand-grease lines and grease guns that have to push lubricant through cold steel fittings.
Long service life over extended drain intervals
Trucking and equipment fleets compress maintenance windows to keep equipment in service. The polymeric chemistry is designed to remain intact between service visits, so chassis points stay protected even when the next greasing is delayed. That tenacity is part of the trade-off: this is a tackier grease than commodity lithium-complex products, and it is engineered to stay rather than flow easily through automated equipment.
Recommended applications and service intervals
GPTR1 is built for mixed fleets in severe service. Use it on heavy-duty over-the-road trucks and trailers, delivery fleets, dump trucks, refuse haulers, utility fleets, emergency service vehicles, sewer and septic trucks, snow-removal vehicles, wreckers, municipal service vehicles, equipment haulers, cement mixer trucks, and airport support vehicles. Greasing points include heavily loaded chassis fittings, wheel bearings, axle assemblies, universal joints, pivot pins, fifth-wheel hitch plates, steering linkages, spring pins, king pins, ball joints, water-pump bearings, and other heavy-duty greased components.
- Pumps best in ambient temperatures above 0 °F, which makes the NLGI #1 grade the cold-climate choice for the polymeric truck/chassis line.
- For warmer operating ranges where the equipment will see ambient above 40 °F most of the time, the NLGI #2 version (GPTR2) is the closer match.
- Not recommended for automatic or centralized lubrication systems on heavy equipment unless the system is specifically designed to pump a tackier grease. A heavy follower plate may be needed when pumping from larger packages.
- Maintenance practice: wipe fittings clean before injecting grease, keep bearing housings one-third to one-half full, and avoid over-greasing because excessive heat buildup can result. To match the right grease and components to a vehicle or piece of equipment, use the AMSOIL vehicle lookup guide.
GPTR1 is compatible with many other grease types, but mixing greases of different thickener chemistries is not best practice. When changing over from another grease, clean components of the old grease or flush by injecting a liberal amount of fresh polymeric grease while the mechanism operates. Monitor for inconsistency during the transition. Pair chassis greasing with the right bypass-protected oil filter and engine oil for the truck or piece of equipment, and follow OEM grease-fitting intervals as the baseline.
Typical technical properties
| Property | Value |
|---|
| NLGI Grade | 1 |
| Thickener | Calcium-Sulfonate Complex |
| Penetration, worked 60 strokes (ASTM D217) | 310-340 |
| Base Oil Viscosity at 40 °C (104 °F), cSt (ASTM D445) | 68 |
| Timken OK Load Test, lbs. (ASTM D2509) | 65 |
| Four-Ball Weld Point, kgf (ASTM D2596) | 620 |
| Dropping Point, °C (°F) (ASTM D2265) | 260 (500) |
| Water Washout, % (ASTM D1264) | 7 |
| Corrosion Test (ASTM D1743) | Pass |
Order AMSOIL NLGI #1 Synthetic Polymeric Truck, Chassis, and Equipment Grease
GPTR1 is stocked in 14-oz. cartridges (single, case of 10, and packs of 40), 35-lb. lugs, 120-lb. kegs, and 400-lb. drums for fleet and shop use. AMSOIL products are backed by the AMSOIL Limited Liability Warranty. Use the AMSOIL grease guide for thickener, NLGI grade and water-resistance comparisons across the product family. Buy online
Customer reviews
Best grease
I own heavy equipments, after I started using this product îl never go back to others, best quality on the market
By Radu from Portland Oregon on June 17, 2025.
Would recommend this to a friend.
Great product.
My truck takes a beating, with no evidence of any problems since I started using this grease.
By Sherman on July 11, 2024.
Would recommend this to a friend.
Good
Been using this and #2 on my truck for 2 years and seems to be doing great
By Dalton from Indiana on June 10, 2024.
Would recommend this to a friend.
Read all 13 reviews
Frequently asked questions
What is NLGI #1 grease?
NLGI grade is the National Lubricating Grease Institute consistency rating, set by ASTM D217 worked-penetration measurement. NLGI #1 is one step softer than the more common NLGI #2. GPTR1 has a worked penetration of 310-340, which gives it better cold-temperature pumpability and easier flow through grease lines while still providing the film thickness needed for chassis components.
What is the difference between GPTR1 (NLGI #1) and GPTR2 (NLGI #2)?
Same calcium-sulfonate complex thickener, same polymeric chemistry and same Timken OK Load (65 lbs.), Four-Ball Weld Point (620 kgf) and dropping point (260 °C). The differences are consistency, base-oil viscosity, and water washout. GPTR1 is softer (NLGI #1, 68 cSt base oil) and pumps best above 0 °F. GPTR2 is firmer (NLGI #2, 220 cSt base oil) and pumps best above 40 °F, with a lower 3% water washout rating.
What is calcium-sulfonate complex grease?
Calcium-sulfonate complex is a high-performance grease thickener built from overbased calcium sulfonates. It produces inherent rust and corrosion protection, a high dropping point, strong extreme-pressure capability and excellent water resistance without leaning on the same anti-wear additive packages used in lithium-complex greases. That chemistry pairs with the polymeric component in GPTR1 to deliver the cling, shock-load resistance and water-washout numbers shown in the technical-properties table above.
Is GPTR1 compatible with lithium-complex grease?
GPTR1 is compatible with many other types of grease, but standard practice when switching thickener chemistries is to clean components of the old grease or flush by injecting a liberal amount of fresh polymeric grease while the mechanism operates, then monitor for any inconsistency. Mixing greases of different thickener systems in service is not the goal.
Can GPTR1 be used in centralized or automatic lubrication systems?
GPTR1 is not recommended for automatic or centralized lubrication systems on heavy equipment unless the system is specifically designed to pump a tackier grease. The same polymeric chemistry that keeps the grease in place also makes it harder to push through smaller-diameter lines and standard pump heads. For larger packages, a heavy follower plate may be necessary to maintain prime.
Can GPTR1 be used on wheel bearings?
Yes. Wheel bearings on heavy-duty trucks and trailers are listed in the application set for GPTR1, along with axle assemblies, U-joints, fifth-wheel plates, kingpins, ball joints, and water-pump bearings. Pack housings one-third to one-half full and avoid overpacking.
How cold can GPTR1 be used?
GPTR1 pumps best in temperatures above 0 °F. Below that, expect harder pumping through grease guns and chassis lines. Operators running well below 0 °F on a regular basis should plan service procedures around warm-up, heated grease lines or shop-temperature greasing rather than expecting cold-soaked grease guns to flow normally.
