AMSOIL Authorized Dealer
ALAN WILLIAMS TOMBALL, TX 77375
225-441-6397

Technical Field Guide — Heavy-Duty Diesel Lubricants

AMSOIL
Diesel Truck Oil
Cummins · Duramax · Powerstroke — Complete Guide

Engine-specific AMSOIL recommendations for every major diesel truck platform. Correct viscosity by model year, DPF/EGR/DEF compatibility explained, drain interval guidance, towing considerations, and a full product matrix. Written by a 20-year AMSOIL dealer who uses this oil in working diesel trucks.

▼  Find Your Engine — Fast

■Cummins 2007–2018: Max-Duty 15W-40 (DME)

■Cummins 2019+: Max-Duty 10W-30 (AEL) — TSB required

■Duramax LB7–LML (2001–2016): Max-Duty 15W-40 (DME)

■Duramax L5P (2017+): Max-Duty 5W-30 (AMSD)

■Powerstroke 6.7 (2011+): Max-Duty 10W-30 (AEL)

■Cold weather any engine: Max-Duty 5W-40 (DEO) below 0°F

AW

Alan Williams

AMSOIL Direct Jobber #1243776  ·  Tomball TX  ·  Since 2004

Diesel truck clients across Texas & Gulf Coast  ·  Cummins, Duramax & Powerstroke experience  ·  225-441-6397

Updated May 2026

Section 01

Why Diesel Engines Demand
Different Oil Than Gas Engines

A diesel pickup engine is not a gas engine with a different fuel. It operates at fundamentally higher compression ratios, generates dramatically more soot, runs hotter under load, and creates acids from combustion at a rate that would destroy a passenger-car oil in short order. The oil formulation requirements are entirely different.

🐴

Extreme Soot Load

Diesel combustion produces soot that enters the oil through the ring pack. Modern EGR systems recirculate exhaust gases, dramatically increasing soot load. Without advanced dispersants, soot agglomerates into abrasive particles and causes accelerated wear on rings, liners, and bearings.

🔥

Higher Heat & Pressure

Diesel engines operate at compression ratios of 15:1 to 23:1 versus 8:1 to 12:1 for gas engines. Turbochargers add further heat and pressure. Oil temperatures routinely reach 230–260°F under towing load — conditions that destroy conventional oils rapidly.

⚗️

Acid Production

Diesel combustion byproducts include sulfur compounds that form acids in the oil. These acids attack bearing surfaces and promote corrosion. Diesel oil requires significantly higher Total Base Number (TBN) reserves than gas engine oil to neutralize these acids throughout the drain interval.

🔥

Emissions System Demands

2007+ diesel trucks use DPF, EGR, SCR, and DEF systems that require low-ash (SAPS) oil. High-ash oil clogs DPF filters and contaminates catalysts. API CK-4 certification ensures compatibility with all modern emissions systems.

🔒

Viscosity Shear & Stability

Diesel transmissions and injection systems create extreme shear forces that permanently thin ordinary oil. A 15W-40 oil must remain a 40-grade oil at operating temperature throughout the drain interval — not thin down to 30-grade or below as cheaper oils do under shear.

☁️

Cold-Start Demands

Diesel engines are hard to start in extreme cold and create elevated wear in the first seconds of operation if oil doesn’t flow quickly to bearings and injector components. Low pour-point synthetic base oils are critical for cold-climate diesel operation.

The practical consequence: Never use a passenger-car motor oil in a diesel truck, even if the viscosity grade matches. Automotive API SP oils lack the detergency, TBN reserve, and soot-handling chemistry required by diesel engines. Always use an oil carrying a diesel API rating — API CK-4 for 2017+ and CJ-4 for 2007–2016 — from a product formulated for diesel applications.

Section 02 — Critical Spec Knowledge

API CK-4, DPF, EGR, SCR & DEF
What Every Diesel Owner Must Know

Modern diesel pickup trucks built since 2007 are equipped with a suite of emissions control systems. The oil you use must be compatible with all of them — and AMSOIL Signature Series Max-Duty meets every one of these requirements.

System What It Does Oil Requirement AMSOIL Max-Duty
DPF
Diesel Particulate Filter		 Traps particulate matter from exhaust. Requires periodic regeneration (burning off trapped soot). Low-SAPS oil (low sulfated ash, phosphorus, sulfur). API CK-4 compliant. High-ash oil clogs DPF. ✔ Compatible
EGR
Exhaust Gas Recirculation		 Recirculates a portion of exhaust back into the intake to reduce NOx emissions. Increases soot load in oil significantly. High-detergency, soot-dispersant oil. Must resist soot-induced viscosity increase throughout drain interval. ✔ Compatible
SCR
Selective Catalytic Reduction		 Converts NOx to nitrogen and water using DEF (Diesel Exhaust Fluid / AdBlue). Used in 2010+ diesel trucks. Low-ash API CK-4 oil to protect the SCR catalyst from contamination. ✔ Compatible
DEF / AdBlue
Diesel Exhaust Fluid		 Urea-water solution injected into exhaust stream to enable SCR operation. Separate from engine oil. Oil must not contaminate the DEF system. API CK-4 ensures correct formulation. ✔ Compatible
API CK-4 Current top-tier diesel oil specification for 2017+ engines. Backward compatible with CJ-4, CI-4+, and older specs. Required for all 2017+ diesel pickups. Provides improved oxidation resistance, shear stability, and DPF compatibility vs older specs. ✔ Certified

Never use API FA-4 oil in a pickup truck diesel. FA-4 is a separate low-viscosity diesel spec designed for linehaul semi trucks optimized for fuel economy at highway cruise. FA-4 oils are thinner and NOT backward compatible with CK-4 or CJ-4. Using FA-4 in a Cummins, Duramax, or Powerstroke pickup is a serious error. All AMSOIL diesel oils recommended on this page are CK-4, not FA-4.

Section 03 — Cummins Engines

AMSOIL for 6.7L Cummins
(Ram 2500/3500 — 2007.5–2026)

⚠ Critical: 2019+ Cummins owners — do NOT use 15W-40. Cummins issued Technical Service Bulletin TSB 09-011-20 (July 2020) specifying that 2019 and newer 6.7L Cummins engines require 10W-30 oil meeting Cummins CES 20086 specification. Using 15W-40 in a 2019+ Cummins does not meet manufacturer specification and may affect warranty coverage. The correct AMSOIL product for 2019+ Cummins is Max-Duty 10W-30 (AEL).

6.7 Cummins — AMSOIL Recommendation by Model Year

Model Year Cummins Spec Viscosity (above 0°F) Viscosity (below 0°F) AMSOIL Product Oil Capacity
2007.5–2018 CES 20081
API CJ-4 / CK-4		 15W-40 5W-40 DME (15W-40)
DEO (5W-40)		 12 qts
2019–2026 ⚠ CES 20086
API CK-4 required		 10W-30 5W-40 AEL (10W-30)
DEO (5W-40)		 12 qts

⚠ TSB 09-011-20 issued July 2020: 2019+ 6.7 Cummins must use 10W-30 meeting CES 20086. Do not use 15W-40 in these engines. Verify your model year before ordering.

Why AMSOIL for Cummins?

The 6.7 Cummins is one of the most capable diesel engines ever built — but it is also one of the most demanding in terms of oil quality. The EGR system in 2007+ Cummins engines routes a significant portion of exhaust gases back through the intake, loading the oil with soot at a rate far higher than a naturally aspirated diesel. AMSOIL Signature Series Max-Duty handles this with a boosted detergent/dispersant additive package that keeps soot particles suspended rather than allowing them to agglomerate into wear-causing clusters.

→ Shop AMSOIL Max-Duty 15W-40 for Cummins (DME) at AMSOIL.com

→ Shop AMSOIL Max-Duty 10W-30 for 2019+ Cummins (AEL) at AMSOIL.com

Section 04 — Duramax Engines

AMSOIL for 6.6L Duramax
(Silverado/Sierra 2500/3500 — 2001–2026)

The Duramax engine family spans 25+ years and multiple generations, each with different viscosity requirements. The most significant change occurred with the L5P generation in 2017, which shifted from 15W-40 to a lighter 5W-30 specification to meet tighter emissions and fuel economy standards.

Generation Years Viscosity AMSOIL Product Oil Capacity
LB7 2001–2004 15W-40 DME 10 qts
LLY / LBZ 2004.5–2007 15W-40 DME 10 qts
LMM 2007.5–2010 15W-40 DME 10 qts
LML 2011–2016 15W-40 DME 10 qts
L5P ★ 2017–2026 5W-30 AMSD or AEL 10 qts

★ L5P Duramax (2017+) specifies 5W-30 meeting Duramax GM6094M spec. Do not use 15W-40 in L5P engines. Always verify capacity with dipstick after fill — capacities shown are approximate with filter.

Allison Transmission — What Oil to Use

The Allison 1000 series automatic transmission used in Duramax trucks requires Allison TES 295 or TES 468 approved transmission fluid. AMSOIL OE Multi-Vehicle Automatic Transmission Fluid meets Allison TES 295. For extended drain use, AMSOIL Signature Series Multi-Vehicle ATF meets TES 295 and provides superior protection under the sustained high-heat conditions of heavy towing — where transmission fluid temperatures routinely exceed 250°F in grade climbing or max-payload scenarios.

→ Shop AMSOIL Max-Duty 15W-40 for Duramax (DME) at AMSOIL.com

Section 05 — Powerstroke Engines

AMSOIL for 6.7L Powerstroke
(F-250/350/450/550 — 2011–2026)

The Ford 6.7 Powerstroke is Ford’s first in-house diesel engine, replacing the International-sourced 6.4 in 2011. It is a significantly different engine from the Cummins and Duramax in both architecture and oil specification — Ford specifies 10W-30 for the 6.7 Powerstroke, meeting Ford WSS-M2C171-F1.

Do not use 15W-40 in a 6.7 Powerstroke. Ford specifies 10W-30 meeting Ford WSS-M2C171-F1 for the 6.7 Powerstroke. 15W-40 does not meet this specification and is not compatible with Ford’s oil system design for this engine.

Model Year Ford Spec Viscosity AMSOIL Product Oil Capacity
2011–2014 Ford WSS-M2C171-F1
API CJ-4		 10W-30 AEL (10W-30) 13 qts
2015–2019 Ford WSS-M2C171-F1
API CK-4		 10W-30 AEL (10W-30) 13 qts
2020–2026 Ford WSS-M2C171-F1
API CK-4		 10W-30 AEL (10W-30) 13.1 qts

Important: The 6.7 Powerstroke takes a large oil filter that holds approximately 1.5 quarts of oil. When filling a dry engine or replacing filter, pre-fill the filter with clean oil before installation to minimize oil pressure lag at first startup.

→ Shop AMSOIL Max-Duty 10W-30 for Powerstroke (AEL) at AMSOIL.com

Section 06

Complete Engine-by-Engine
AMSOIL Product Matrix

Engine Years Viscosity AMSOIL Code Product Name Capacity
Cummins (Ram 2500/3500)
6.7 Cummins 2007.5–2018 15W-40 DME Signature Series Max-Duty 15W-40 12 qt
6.7 Cummins ⚠ 2019–2026 10W-30 AEL Signature Series Max-Duty 10W-30 12 qt
6.7 Cummins (cold) All years below 0°F 5W-40 DEO Signature Series Max-Duty 5W-40 12 qt
5.9 Cummins 1989–2007 15W-40 DME Signature Series Max-Duty 15W-40 11 qt
Duramax (Silverado/Sierra 2500/3500)
LB7 Duramax 2001–2004 15W-40 DME Signature Series Max-Duty 15W-40 10 qt
LLY / LBZ Duramax 2004.5–2007 15W-40 DME Signature Series Max-Duty 15W-40 10 qt
LMM / LML Duramax 2007.5–2016 15W-40 DME Signature Series Max-Duty 15W-40 10 qt
L5P Duramax ★ 2017–2026 5W-30 AMSD Signature Series Max-Duty 5W-30 10 qt
Powerstroke (F-250/350/450/550)
6.7 Powerstroke 2011–2026 10W-30 AEL Signature Series Max-Duty 10W-30 13 qt
6.4 Powerstroke 2008–2010 15W-40 DME Signature Series Max-Duty 15W-40 15 qt
6.0 Powerstroke 2003–2007 15W-40 DME Signature Series Max-Duty 15W-40 15 qt
7.3 Powerstroke 1994–2003 15W-40 DME Signature Series Max-Duty 15W-40 15 qt

⚠ 2019+ Cummins: TSB 09-011-20 prohibits 15W-40 — use AEL 10W-30. ★ L5P Duramax (2017+): specifies 5W-30, not 15W-40. Oil capacities are approximate with filter replacement. Always verify with dipstick and owner manual.

Section 07

Complete AMSOIL Diesel
Product Lineup

Every AMSOIL diesel oil product, catalog code, API rating, and recommended application.

DME
Signature Series Max-Duty 15W-40
API CK-4

AMSOIL Signature Series Max-Duty 15W-40

The flagship diesel oil for classic Cummins, Duramax (pre-L5P), and older Powerstroke engines. 6× better wear protection than required by the Detroit Diesel DD13 Scuffing Test. 76% less oil consumption than required by API CK-4 in the Caterpillar-1N test. Extended drain rated to 2× OEM interval, not to exceed 25,000 miles or 1 year. Compatible with all exhaust aftertreatment systems including DPF, EGR, SCR, and DEF. Rated for Cummins CES 20081/20076, Allison TES 439, and all major OEM specs.

Code: DME / DMEQT / DMEG
API: CK-4/SN · CJ-4 · CI-4+
Drain: 2× OEM (max 25,000 mi/yr)
Best for: Cummins 2007–2018, Duramax LB7–LML, Powerstroke 6.0/6.4

AEL
Signature Series Max-Duty 10W-30
API CK-4

AMSOIL Signature Series Max-Duty 10W-30

Required for 2019+ 6.7 Cummins (TSB 09-011-20) and 6.7 Powerstroke (all years). Meets Cummins CES 20086 and Ford WSS-M2C171-F1 specifications. Same Signature Series Max-Duty additive technology as DME — identical wear protection, soot control, and DPF/EGR compatibility — in the 10W-30 viscosity grade required by these engines. Better cold-flow than 15W-40 without sacrificing hot-film protection at operating temperature.

Code: AEL / AELQT / AELG
API: CK-4/SN · CJ-4 · CI-4+
Best for: Cummins 2019+, Powerstroke 6.7 (all years)

DEO
Signature Series Max-Duty 5W-40
API CK-4

AMSOIL Signature Series Max-Duty 5W-40

The cold-climate diesel oil for all Cummins and older Powerstroke/Duramax engines operating below 0°F (−18°C). The 5W cold rating provides significantly better cold-cranking ability than 15W-40 — 4× better cold-cranking in published tests — while maintaining a full 40-grade protective film at operating temperature. Ideal for North Dakota, Minnesota, Montana, Canadian operators, and any diesel truck starting in extreme cold.

Code: DEO / DEOQT / DEOG
API: CK-4/SN · CJ-4 · CI-4+
Best for: All diesel pickups in sub-zero climates

AMSD
Signature Series Max-Duty 5W-30
API CK-4

AMSOIL Signature Series Max-Duty 5W-30

Required for 2017+ Duramax L5P engines specifying 5W-30 (GM Duramax GM6094M spec). Also suitable for newer diesel applications requiring lighter viscosity grades for fuel economy compliance. Full Signature Series Max-Duty chemistry — extended drain intervals, superior soot control, API CK-4 certified, DPF/EGR/SCR compatible. Provides excellent cold-start protection with broader temperature range than 15W-40.

Code: AMSD
API: CK-4/SN
Best for: Duramax L5P (2017+)

Section 08 — Towing & Hauling

AMSOIL for Towing & Hauling
Drivetrain Protection Under Load

Towing is the most severe operating condition for a diesel truck drivetrain. Engine oil temperature climbs 40–80°F higher under sustained towing load. Transmission fluid in an Allison under max-payload towing regularly exceeds 250°F. Rear axle fluid in a Dana or AAM differential under a loaded fifth-wheel can approach 300°F on a mountain grade. Each of these conditions demands oil that doesn’t thin and fail under heat.

Engine Oil

Max-Duty Signature Series

Use your engine’s correct viscosity grade (DME, AEL, or DEO per the tables above). The high HTHS viscosity and shear-stable synthetic base stocks maintain protective film thickness at towing temperatures where cheaper oils thin and fail.

DME, AEL, or DEO depending on engine

Automatic Transmission

Signature Series ATF

Allison 1000 series transmissions require TES 295-approved fluid. AMSOIL Signature Series Multi-Vehicle ATF meets this spec and provides superior thermal stability at the sustained high temperatures of mountain grade towing. Change interval: 2× OEM.

Code: ATF / ATFQT

Rear Axle / Front Axle

Severe Gear 75W-90

AMSOIL Severe Gear synthetic gear lube maintains protective film at the extreme temperatures of loaded towing. The proprietary iron-sulfide barrier coating on gear teeth provides a last line of defense under metal-to-metal contact conditions during severe grade towing.

Code: SVG / SVO / SVT (75W-90/110/140)

Diesel Fuel

Diesel Injector Clean

Diesel fuel injectors under sustained towing load are prone to deposit buildup from heat. AMSOIL Diesel Injector Clean restores lost power and efficiency by removing injector deposits — critical for maintaining fuel atomization quality and combustion efficiency under load.

Code: ADF / ADFSC

Alan’s towing recommendation from 20 years in Texas: If you tow regularly in hot weather — summer Texas heat, Arizona, or any sustained grade climbing under load — the single most important upgrade is getting Severe Gear in your axles and making sure your engine oil is current AMSOIL Max-Duty. The axle is the most overlooked component. I have seen Dana 70 rear axles come apart on trucks whose owners religiously maintained their engine oil but never changed their factory-fill gear lube.

Section 09

Extended Drain Intervals
with AMSOIL Diesel Oil

AMSOIL Signature Series Max-Duty is rated for up to 2× the OEM-recommended drain interval in turbo-diesel pickup trucks, not to exceed 25,000 miles or one year, whichever comes first. This means:

Engine OEM Interval AMSOIL Max-Duty Changes Saved/Year*
6.7 Cummins (2007–2018) 7,500 mi 15,000 mi 1 change saved
6.7 Cummins (2019+) 7,500 mi 15,000 mi 1 change saved
6.6 Duramax (LB7–LML) 7,500 mi 15,000 mi 1 change saved
6.6 Duramax L5P (2017+) 7,500 mi 15,000 mi 1 change saved
6.7 Powerstroke 10,000 mi 20,000 mi 1 change saved

*At 15,000 miles/year driving. Extended intervals not recommended for: 2007–2010 Ford 6.4, Dodge 6.7, and GM 6.6 (fuel dilution concerns at extended drain); performance-modified engines; or when using biofuels exceeding B15. Always verify oil condition with analysis if extending beyond 2× OEM interval.

Oil Analysis — The Smart Approach to Extended Drains

For owners wanting to push beyond the published AMSOIL interval — or for high-mileage engines, modified trucks, or unusual operating conditions — oil analysis is the definitive answer. A used-oil analysis from a lab like Blackstone or AMSOIL’s own analysis service tests your specific oil for wear metals, viscosity, TBN, and soot level. It tells you objectively whether the oil has more life or needs changing. Drain intervals can be extended further with clean oil analysis results. For commercial operators managing fleet costs, oil analysis is standard practice.

Section 10 — Comparison

AMSOIL Max-Duty
vs Shell Rotella T6

Shell Rotella T6 is the most widely used synthetic diesel oil in North America. It is the default comparison for any diesel truck owner considering AMSOIL. Here is an honest, data-based comparison.

Comparison Point AMSOIL Max-Duty 15W-40 Rotella T6 5W-40
Base oil type Group IV PAO synthetic Group III synthetic
Wear protection vs DD13 test 6× better than required Meets requirement
Oil consumption (API CK-4 test) 76% less than required Meets requirement
Rated drain interval (pickup truck) Up to 2× OEM (max 25,000 mi) OEM interval
API certification CK-4 / SN CK-4 / SN
DPF / EGR / SCR compatible ✔ Yes ✔ Yes
Retail price per gallon (approx) ~$35–40 (PC: ~$26–30) ~$24–28
Cost per mile of protection Lower (2× drain interval) Higher (OEM interval only)

The verdict on Rotella T6 vs AMSOIL: Rotella T6 is a quality oil that meets API CK-4 and protects diesel engines well at OEM intervals. At the 7,500-mile change interval most truck manufacturers specify, the performance gap between Rotella T6 and AMSOIL Max-Duty is real but not catastrophic. Where AMSOIL wins decisively: (1) the extended drain interval — 15,000 miles versus Rotella’s OEM-only interval means fewer changes at lower total cost per mile; (2) superior base oil chemistry (Group IV PAO vs Group III) which delivers measurably better shear stability and thermal resistance at higher temperatures and over longer drains; (3) 6× better wear protection in DD13 testing. If your goal is maximum protection, extended drains, and lower total oil change cost, AMSOIL wins on all three counts.

Section 11

Frequently Asked Questions
Diesel Truck Oil

10 questions. Engine-specific answers for Cummins, Duramax, and Powerstroke owners.

For a 2022 Ram 6.7 Cummins, use AMSOIL Signature Series Max-Duty 10W-30 (AEL). Cummins TSB 09-011-20 (issued July 2020) specifies that all 2019 and newer 6.7 Cummins engines must use 10W-30 meeting Cummins CES 20086 specification. Do not use 15W-40 in a 2019+ Cummins. The AEL product meets CES 20086, is API CK-4 certified, and carries AMSOIL’s full extended drain warranty. Oil capacity is approximately 12 quarts with filter. For cold weather below 0°F, switch to AMSOIL Max-Duty 5W-40 (DEO).

For the 2020 Silverado 3500 with the 6.6L L5P Duramax, use AMSOIL Signature Series Max-Duty 5W-30 (AMSD). The L5P Duramax (2017+) specifies 5W-30 meeting the GM Duramax GM6094M / dexos2 specification — not 15W-40. Oil capacity is approximately 10 quarts with filter. For the Allison 1000 transmission in your truck, use AMSOIL Signature Series Multi-Vehicle ATF (ATF) which meets Allison TES 295. If you also want gear lube protection under towing, AMSOIL Severe Gear 75W-90 (SVG) is the correct product for your rear and front differentials.

For all 6.7 Powerstroke engines (2011–2026), use AMSOIL Signature Series Max-Duty 10W-30 (AEL). Ford specifies 10W-30 meeting Ford WSS-M2C171-F1 for the 6.7 Powerstroke — do not use 15W-40 in this engine. Oil capacity is approximately 13 quarts with filter — note the large Powerstroke filter holds about 1.5 quarts, so pre-fill with fresh oil before installation to minimize oil pressure lag on first startup. AMSOIL Severe Gear 75W-90 (SVG) is correct for your Dana rear axle.

Yes. All AMSOIL Signature Series Max-Duty diesel oils are API CK-4 certified with a low-SAPS (low sulfated ash, phosphorus, sulfur) formulation that is fully compatible with Diesel Particulate Filters (DPF), Exhaust Gas Recirculation (EGR), Selective Catalytic Reduction (SCR), and Diesel Exhaust Fluid (DEF) systems. The low-ash formulation is specifically engineered not to plug DPF filters or contaminate SCR catalysts during filter regeneration cycles. API CK-4 certification is mandatory for 2007+ diesel trucks precisely because of these emissions system compatibility requirements.

AMSOIL Signature Series Max-Duty contains a boosted detergent and dispersant additive package specifically engineered to handle the elevated soot loads created by EGR systems. The dispersants keep individual soot particles suspended in the oil, preventing them from agglomerating into larger clusters that cause abrasive wear on rings, liners, and bearings. Independent testing shows AMSOIL Max-Duty maintains its specified viscosity grade throughout extended drain intervals even under high EGR soot loading — a key indicator of effective soot control. In comparison testing by Nordic Waste (Duluth diesel fleet), AMSOIL demonstrated superior TBN retention and was the only oil tested to remain within its specified viscosity range throughout the full test interval.

AMSOIL Ea Oil Filters (Ea = Absolute Efficiency) are rated for the full extended drain interval of AMSOIL oil — you do not need to change the filter mid-interval. For Cummins trucks, the EAO141 covers most 6.7 Cummins applications. For Duramax, the EAO57 covers most 6.6 Duramax. For Powerstroke, the EAO57 covers most 6.7 Powerstroke. Always verify using the AMSOIL vehicle lookup at amsoil.com before ordering — filter fitment varies by model year and engine configuration. Using an AMSOIL Ea filter with AMSOIL oil is the complete solution for extended drain interval protection.

No. The Magnuson-Moss Warranty Act prohibits manufacturers from voiding your vehicle warranty solely because you used a different brand of oil, provided that oil meets the required API specification. AMSOIL Max-Duty diesel oils are API CK-4 certified and meet all OEM specifications for Cummins, Duramax, and Powerstroke diesel trucks. Keep your AMSOIL purchase receipts as documentation. The one requirement: you must use the correct product for your specific engine (e.g., AEL 10W-30 for a 2019+ Cummins, not DME 15W-40) to maintain compliance with OEM specifications.

Yes — for most diesel truck owners, when total cost is calculated correctly. AMSOIL costs more per gallon than Rotella T6, but AMSOIL is rated for twice the drain interval. At 7,500-mile OEM intervals, a truck driving 15,000 miles per year needs 2 Rotella T6 changes. With AMSOIL at 15,000-mile intervals, it needs 1 change. That means fewer gallons of oil purchased per year, fewer filters, fewer hours of shop time or DIY labor, and fewer waste oil disposal events. When you factor in AMSOIL Preferred Customer pricing (25% off) through Lube Oil Sales, the per-gallon price gap with Rotella narrows further. For trucks with higher mileage or that tow regularly, AMSOIL’s superior wear protection offers real engine longevity value that compounds over years.

API CK-4 was introduced in December 2016 and is the current top-tier diesel oil specification, replacing CJ-4 for 2017 and newer engines. CK-4 offers improved oxidation resistance, shear stability, and aeration control compared to CJ-4. CK-4 is also backward compatible — it is safe to use in engines that previously specified CJ-4 (2007–2016 trucks). For 2007–2016 diesel trucks, you can use either CJ-4 or CK-4 certified oil. For 2017+ diesel trucks, CK-4 is required. Never use FA-4 in a pickup truck diesel — FA-4 is for linehaul semi-trucks only and is not backward compatible with CK-4 or CJ-4 applications.

Join as an AMSOIL Preferred Customer through Lube Oil Sales (Dealer #1243776) for $20/year. You immediately save 25% on every AMSOIL product permanently — including all diesel oils, filters, gear lubes, and additives. At Preferred Customer pricing, AMSOIL Max-Duty 15W-40 in a 2.5-gallon jug costs approximately $70 versus $95 retail. For a diesel truck needing 10–15 quarts per change, those savings add up quickly. Alan Williams can also take orders by phone at 225-441-6397 and ship factory-direct to your door.

 

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AMSOIL and the AMSOIL logo are registered trademarks of AMSOIL INC., Superior WI. LubeOilSales.com is an independent AMSOIL dealership not owned or endorsed by AMSOIL INC. Cummins, Duramax, Powerstroke, Ram, Ford, Chevrolet, GMC, Allison, Dana, and all other manufacturer names are trademarks of their respective owners. LubeOilSales.com has no affiliation with these manufacturers. Engine specifications, viscosity requirements, and drain intervals are based on published OEM documentation and AMSOIL product data current as of May 2026 — always verify with your owner manual and current AMSOIL product data sheets. Cummins TSB 09-011-20 information sourced from published Cummins technical documentation. Alan Williams is an Authorized AMSOIL Independent Direct Jobber (Dealer #1243776), Tomball TX 77375.