API CK-4 Is the Base
CK-4 defines a broad industry performance category. Mack EOS-4.5 adds manufacturer-specific requirements for Mack engines.
Mack Engine Oil Specification
Mack EOS-4.5
Mack EOS-4.5 is the heavy-duty engine oil specification used on Mack MP7, MP8 and MP10 diesel engines. It belongs to the API CK-4 generation of diesel oils but adds Mack-specific requirements, so a generic CK-4 claim alone should not be treated as proof of EOS-4.5 compliance.
If your Mack calls for EOS-4.5, use an engine oil that specifically lists Mack EOS-4.5 for the required viscosity and operating conditions. Do not choose the oil by API CK-4 alone.
Specification Basics
What Is Mack EOS-4.5?
EOS means Engine Oil Specification. Mack uses its own engine-oil requirements in addition to the broader API diesel-oil categories used throughout the industry.
EOS-4.5 arrived with the newer low-emissions diesel-oil generation associated with API CK-4. It is used on modern Mack MP-series engines and supersedes the older Mack EOS-4 / EO-O generation for applications where Mack specifies EOS-4.5.
Mack Approval Matters
Two oils can both be CK-4 while only one lists Mack EOS-4.5. Check the product data sheet or Mack approval information rather than assuming all CK-4 oils are interchangeable.
Designed for Modern Diesels
EOS-4.5 oils are intended for modern emissions-equipped heavy-duty engines operating with EGR, diesel particulate filters and SCR aftertreatment.
The Important Part
“CK-4” and “Mack EOS-4.5” are not two names for exactly the same thing. CK-4 is the industry category. EOS-4.5 is Mack's engine-oil requirement for the applicable MP engines.
Mack MP Engines
Which Engines Use EOS-4.5?
Mack MP7
The 11-litre MP7 used in regional, vocational and weight-sensitive Mack applications uses Mack EOS-4.5 where specified by the engine service information.
Mack MP8
The 13-litre-class MP8 is one of Mack's most common heavy-truck engines and is a major EOS-4.5 application.
Mack MP10
The larger MP10 platform also uses Mack EOS oil specifications. Oil-pan size affects the published maintenance interval.
Check the Exact Model Year and Engine Label
Do not select an oil solely because the truck has an MP-series engine. Mack has used different oil specifications across engine generations and fuel-economy configurations. Verify the engine model, model year and required specification before moving to a lower-viscosity oil.
Specification Comparison
EOS-4.5 vs API CK-4
| Requirement | API CK-4 | Mack EOS-4.5 |
|---|---|---|
| Who Defines It? | American Petroleum Institute | Mack Trucks |
| Type | Industry-wide diesel engine-oil category | Manufacturer-specific engine-oil specification |
| Diesel Emissions Systems | Designed for modern emissions-equipped diesels | Applied to compatible Mack MP engines and aftertreatment systems |
| Does CK-4 Automatically Mean EOS-4.5? | No | The product must specifically identify the Mack requirement |
| Typical Heavy-Truck Grade | 15W-40 and 10W-30 are common | Follow Mack viscosity recommendations for the exact engine |
Fleet Rule
If the truck requires EOS-4.5, start with EOS-4.5 compliance. Then choose the correct viscosity for the engine, climate and duty cycle.
Mack + Volvo
EOS-4.5 and Volvo VDS-4.5
Mack is part of Volvo Group, and Mack MP engines share substantial engineering with Volvo's heavy-duty engine family. That is why many heavy-duty oils list both Mack EOS-4.5 and Volvo VDS-4.5.
They should still be treated as separate manufacturer specifications when checking a product data sheet. Do not assume an oil satisfies Mack EOS-4.5 simply because another Volvo specification appears on the label.
Oil Viscosity
What Viscosity Should You Use?
There is no single viscosity that should be assigned to every EOS-4.5 Mack. The correct grade depends on the engine generation, ambient temperature, duty cycle and Mack's recommendations for that specific application.
15W-40
The traditional heavy-duty choice and a common grade in Mack MP engines. It remains a strong choice for loaded highway, regional and vocational work when permitted by Mack.
10W-30
A lower-viscosity CK-4 grade used in many heavy-duty diesel applications where the engine manufacturer permits it. It can provide better cold-start flow than 15W-40.
5W-40
A full-synthetic grade that combines SAE 40 operating-temperature viscosity with improved cold-temperature cranking and flow.
Do Not Confuse Lower Viscosity With FA-4 Approval
A viscosity such as 5W-30 or 10W-30 does not by itself tell you whether an oil is CK-4 or FA-4. Read the actual API category and Mack specification before using it.
Maintenance Intervals
Mack EOS-4.5 Oil Change Intervals
Mack does not use one universal 25,000-mile oil-change interval for EOS-4.5 engines. Current Mack service information separates engine-oil service by duty cycle, fuel economy, oil type and oil-pan capacity.
| 42 L / 44 Qt Oil Pan | Normal Duty | Heavy Duty | Severe Duty |
|---|---|---|---|
| Mack EOS-4.5 Premium Oil | 60,000 miles | 45,000 miles | 35,000 miles |
| Other Mack-Approved EOS-4.5 Oil | 55,000 miles | 40,000 miles | 30,000 miles |
Mack identifies normal, heavy and severe duty partly by fuel economy. The maintenance schedule also states that if idle time exceeds 30 percent, the next lower drain interval should be used.
Oil Analysis Is Still Valuable
Published maximums are not a substitute for knowing what is happening inside a working engine. Fleets extending service or operating with high idle time, contamination risk or severe vocational duty can use oil analysis to monitor wear metals, viscosity, soot and contamination.
AMSOIL Diesel Oils
DME · 15W-40
ADP · 15W-40
Commercial Grade
AMSOIL Oils for Mack EOS-4.5 Applications
AMSOIL currently lists Mack EOS-4.5 among the applications for multiple heavy-duty diesel oils. Match the viscosity to the engine before ordering.
Signature Series Max-Duty
AMSOIL's top-tier 100% synthetic diesel oil for hard-working commercial equipment. Signature Series is formulated for severe operation, viscosity control, low oil consumption and extended-drain capability when properly managed.
- 100% synthetic
- 15W-40
- Heavy-duty diesel service
- 6X wear-protection claim based on Detroit Diesel DD13 scuffing testing
Heavy-Duty Synthetic
AMSOIL Heavy-Duty Synthetic 15W-40 is a 100% synthetic diesel oil whose current technical data lists Mack EOS-4.5 among its applications.
- 100% synthetic
- API CK-4
- Mack EOS-4.5 listed application
- 4X wear-protection claim based on DD13 scuffing testing
Commercial-Grade Diesel Oil
AMSOIL Commercial-Grade Diesel Oil is a synthetic blend with greater than 50 percent synthetic content. Its current data sheet lists Mack EOS-4.5 among its recommended applications.
- Commercial-value option
- Greater than 50% synthetic content
- Mack EOS-4.5 listed application
- Designed for OEM drain intervals
Running a Fleet?
Use AMSOIL's heavy-duty lookup to confirm the engine, viscosity, capacity and product recommendation before ordering for multiple Mack units.
Frequently Asked Questions
Mack EOS-4.5 Questions
What is Mack EOS-4.5?
Mack EOS-4.5 is a Mack-specific heavy-duty engine-oil specification used on applicable MP7, MP8 and MP10 diesel engines. It belongs to the CK-4 generation of heavy-duty oil standards but should not be treated as identical to generic API CK-4.
Is CK-4 the same as Mack EOS-4.5?
No. CK-4 is an API industry category. EOS-4.5 is Mack's manufacturer-specific engine-oil requirement. If your engine calls for EOS-4.5, verify that requirement on the oil manufacturer's technical information.
Which Mack engines use EOS-4.5?
EOS-4.5 is used on applicable Mack MP7, MP8 and MP10 engines. The exact requirement depends on engine year and configuration, so confirm it against the engine label or Mack service information.
What viscosity is Mack EOS-4.5 oil?
EOS-4.5 is a performance specification, not a single viscosity. Common heavy-duty grades include 15W-40 and 10W-30, with other viscosities available for specific applications. Follow Mack's recommendation for your engine.
How often should EOS-4.5 oil be changed?
The interval depends on duty cycle, oil type, oil-pan capacity, fuel economy and idle time. Mack's current 42 L / 44 qt schedule reaches 60,000 miles for normal duty with Mack Premium EOS-4.5 oil and 55,000 miles with other Mack-approved EOS-4.5 oil, with shorter intervals for heavy and severe service.
Can EOS-4.5 replace older Mack EOS-4 oil?
Newer Mack-approved oils are commonly used to service engines from the older EOS-4 generation where permitted by Mack. Always confirm the engine's service requirements, particularly on older equipment.
Is Mack EOS-4.5 the same as Volvo VDS-4.5?
They are closely related specifications from manufacturers within Volvo Group, and many diesel oils list both. They should still be checked individually on the product data sheet rather than assumed to be interchangeable names.
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