Coolant specifications - BB00.40-P-0310-01A

Antifreeze with corrosion inhibitor, KFM: Part of the coolant for combustion engines as corrosion protection and antifreeze protection, for lowering the freezing point as well as increasing the boiling point.

Coolant, KM: Mixture of antifreeze with corrosion inhibitor and water for the cooling of engines. Normally, coolants consist of antifreeze with corrosion inhibitor and water. The coolants must perform the following tasks in the cooling system, among other things:

1. Transfer of heat
2. Corrosion and cavitation protection for all components in the cooling system
3. Lowering of freezing point (antifreeze protection)
4. Increasing of boiling point
5. Resistance against microorganisms
6. Stability and durability
7. No foaming

Coolant additives: Anticorrosion agent that can be used mixed with water for special applications. The mixture does not contain any antifreeze protection!

MB approval: Marking of the coolants or antifreezes with corrosion inhibitor that are tested by Daimler AG and approved for corresponding use, see table 1 and 2. On containers with tested brand-name products, you will find a note, e.g. MB approval 325.0.

Table 26 gives an overview of the application of the tested antifreezes with corrosion inhibitor and the maximum change intervals. Note the MB approval before using a coolant. With the right use of tested coolant qualities with MB approval, you maintain the full protection of the cooling system. The vehicles with combustion engine are defined in the assignment across the engine model series Table 1 therefore applies for all vehicles with an OM642 engine, for example, irrespective of the registration of the vehicle.

Sheet No.	Engine series		Change interval years/km
	M100/M200	OM 600
325.0 or 326.0	•	•	15/250.000 Whichever occurs first must be observed; Exception: In the vehicle's maintenance booklet shorter change intervals are stipulated

Coolants or antifreezes with corrosion inhibitor that are listed in table 26 on different sheet numbers must not be blended, as a considerably lowered corrosion protection may ultimately damage the cooling system. In general, mixtures of various antifreezes with corrosion inhibitor offer a lesser performance than the specially adjusted active components of a formulation.

The sheet numbers: 325.x show the antifreeze with corrosion inhibitor, the corresponding sheet number 326.x shows the finally mixed coolant. The antifreezes with corrosion inhibitor must be mixed with water before use.

The coolants and antifreezes with corrosion inhibitor are based on ethylene glycol as the antifreeze protection component, but differ with regard to the other ingredients, e.g. for corrosion protection, table 27.

The coolant must remain in the cooling system year round to protect against corrosion under all operating conditions. Corrosion may lead to poor heat output and engine overheating!

3.1. Mixing ratio 

As a rule the coolant should consist of approx. 50% corrosion inhibitor/antifreeze and 50% water by volume. The water quality must satisfy the requirements in the following chapter. The antifreeze protection of this mixture is good up to approx. -37 °C. Even with extremely low ambient temperatures, not more than 55 vol.-% antifreeze with corrosion inhibitor is to be used. With 55 % antifreeze with corrosion inhibitor, the maximum antifreeze protection, approx.

-45 °C, of a water-based ethylene glycol solution is reached; a higher KFM portion lowers the antifreeze protection and the heat dissipation in the engine worsens.

The boiling point of the coolant increases with the share of antifreeze with corrosion inhibitor. In the vehicle, the coolant is also protected against boiling by means of the pressure in the cooling system. By raising the pressure, the boiling temperature of the coolant can be increased further.

Only approved products offer reliable protection of the cooling system. In special cases (commercial-vehicle engines, no antifreeze specification) coolant additives can be used that are primarily corrosion protection additives.

Clean and, where possible, soft water should be used for preparing the coolant. Drinking water often meets the desired requirements. Information concerning the water quality of drinking water is available from the local water-plant authorities or the official water utilities on request.

If no information is available on the water quality or no suitable water is available, distilled or deionized water is to be used to prepare the coolant.

Sea water, brackish water, brine and industrial waters are not suitable. Salts may promote corrosion or form disruptive deposits.

The analysis values of the water for mixing in coolants must be within the limits of table 29.

1° dH = 1.783 mmol/l alkaline earth ions = 7.147 mg/l Ca² + or 4.336 mg/l Mg²⁺

4.1. Coolant additives for commercial vehicle engines without antifreeze specification 

In year round frost-free climate zones, no antifreeze is required as the cooling systems are adapted to coolants in acc. with sheet 325.x and 326.x. However, an aqueous solution with corrosion protection should only be used in justified exceptional cases. The use of anticorrosion agents in water is limited to the engines named. The use of anticorrosion oil emulsion in acc. with sheet 311.0 is thermally limited. The emulsion must therefore not be used in efficient modern engines.

The blending of different products is not permitted as per sheet 311.0 and 312.0.

During the production of the anticorrosion oil emulsion in acc. with sheet 311.0, the following is to be noted:

When carrying out a complete refill (initial filling or filling after a cleansing operation), an emulsion of 1.0 to 1.5 vol.-% should be prepared. When refilling, an emulsion of 0.5-1.0 vol % should be used. Concentrations that are too high (>1.5 vol.-%) do not improve the corrosion protection, but rather have a negative influence on seals and hoses.

During operation, the corrosion inhibitors of the coolant are consumed and the mixing ratio may be changed due to the evaporation of water. Regular monitoring of the coolant is therefore important for trouble-free operation of the engine.

The inspection of the mixing ratio should be conducted with suitable apparatuses. To do so, the density in acc. with picture 1 or the refractive index in acc. with picture 2 can be used for the determination. The specifications on the mixing ratio may differ slightly for individual coolants from the values in pictures 1 and 2.

Fig 1: KFM/Water Mixture Density Graph

Courtesy of MERCEDES-BENZ USA

Fig 2: Refractive Index Of KFM/Water Mixtures

Courtesy of MERCEDES-BENZ USA

If only 40 vol.-% or more than 55 vol.-% antifreeze with corrosion inhibitor is in the coolant, the mixing ratio must be corrected immediately. To calculate the refill quantity, the following calculation aid can be used:

Calculation of the antifreeze quantity to be refilled with a concentration that is too low (specified: 50 vol. %) 

Fig 3: Calculation Of Antifreeze Quantity To Be Refilled With Low Concentration

Courtesy of MERCEDES-BENZ USA

Example of calculation: 

Fig 4: Example Of Calculation

Courtesy of MERCEDES-BENZ USA

The coolants are biologically-degradable material. All statutory regulations or waste water regulations in each individual country with regard to the disposal of used coolant must be observed. It is recommended to have the possibilities available for disposing of materials explained by the local responsible water authorities.