2021 Freightliner M2 106 — Fluid Type Specs

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	API CK-4; SAE 10W-30 or 15W-40	12-48 quarts (depending on engine)
Engine Coolant	OAT; Cummins CES 14603	28-38 quarts (depending on engine)
Transmission Fluid	Allison TES 668	19-31 quarts (depending on model)
Rear Differential	API GL-5; SAE 75W-90	16-23 quarts (depending on axle)
Brake Fluid	DOT 4	Varies
Power Steering	ATF	3-4 quarts
Washer Fluid	-	6 quarts
Diesel Exhaust Fluid (DEF)	ISO 22241	6-23 gallons

Engine Oil

The 2021 Freightliner M2 106 is available with a few different engine options, but all of them require API service category CK-4 engine oil. This is the latest specification for heavy-duty diesel engine oils and is backward-compatible with previous categories. The most commonly used viscosity grades are 10W-30 and 15W-40, with the latter being preferred for heavier-duty applications or warmer climates. Always consult your owner's manual for the specific viscosity grade recommended for your engine and operating conditions.

It is critical to use an oil that meets the CK-4 specification to ensure proper protection of the engine and its emissions a an oil that meets the CK-4 specification to ensure proper protection of the engine and its emissions system. The use of older-specification oils can lead to premature wear of engine components and can damage the diesel particulate filter (DPF). The oil change interval for the M2 106 is typically between 25,000 and 50,000 miles, depending on the engine and how the vehicle is used. However, it is always best to follow the manufacturer's recommended oil change interval, which can be found in the owner's manual.

Engine Coolant

The M2 106 uses an Organic Acid Technology (OAT) coolant. It is important to not mix this with other coolant types, such as Hybrid Organic Acid Technology (HOAT) or conventional coolants, as this can cause the coolant to gel and clog the cooling system. The recommended coolant for the M2 106 meets Cummins CES 14603 specification.

The cooling system should be flushed and refilled every two years or 250,000 miles, whichever comes first. When topping off the coolant, be sure to use a 50/50 mixture of coolant and distilled water. Do not use tap water, as it can contain minerals that can damage the cooling system.

Transmission Fluid

Most 2021 Freightliner M2 106 trucks are equipped with an Allison automatic transmission. The required fluid for these transmissions is one that meets the Allison TES 668 specification. This is a full-synthetic fluid that is designed for extended drain intervals and severe-duty applications. The use of any other type of fluid can cause damage to the transmission.

The transmission fluid and filter should be changed every 100,000 miles for normal-duty applications and every 50,000 miles for severe-duty applications. Always consult your owner's manual or a qualified technician for the proper service interval for your vehicle.

Rear Differential

The rear differential on the M2 106 requires a gear oil that meets the API GL-5 specification. The most commonly used viscosity grade is 75W-90. The gear oil should be changed every 100,000 miles or every 3 years, whichever comes first.

Brake Fluid

The M2 106 uses DOT 4 brake fluid. This is a glycol-based fluid that is compatible with most other DOT 3 and DOT 5.1 brake fluids. However, it is not compatible with DOT 5 silicone-based brake fluid. The brake fluid should be flushed and replaced every two years.

Power Steering

The power steering system on the M2 106 uses automatic transmission fluid (ATF). The power steering fluid should be checked at every oil change and topped off as needed. The power steering system should be flushed and refilled every two years or 100,000 miles, whichever comes first.

Washer Fluid

Any type of windshield washer fluid can be used in the M2 106.

Diesel Exhaust Fluid (DEF)

If your M2 106 is equipped with a diesel engine, it will have a selective catalytic reduction (SCR) system that requires the use of diesel exhaust fluid (DEF). DEF is a non-toxic solution of 32.5% urea and 67.5% de-ionized water. It is important to use only DEF that is certified by the American Petroleum Institute (API) and meets the ISO 22241 specification. The use of non-compliant DEF can damage the SCR system and may void the vehicle's warranty.

The DEF tank should be refilled as needed. The DEF gauge on the instrument panel will indicate when the DEF level is low. It is important to not let the DEF tank run dry, as this will cause the engine to derate and will eventually prevent the engine from starting.

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