Note: These specifications apply to the Mercedes-Benz, Maybach, AMG, smart, and Setra brands.
WARNING
The tasks that the antifreeze with corrosion inhibitor, coolants or coolant additives have to perform are as important as those of a component. All products that are not listed in the following Specifications for Operating Fluids sheets do not have MB approval and can thus lead to significant restrictions in the engine output and/or to irreparable damage to the engine cooling system.
1. Terms used
Antifreeze with corrosion inhibitor:
Also known as "concentrate". It is part of the coolant for combustion engines, antifreeze with corrosion inhibitor, used for lowering the freezing point and raising the boiling point. Must be mixed with water as per item 3.4.
Coolant:
Mixture of concentrate (or antifreeze) and water for cooling engines.
Coolant additives:
Anticorrosion agent that can be used for special applications mixed with water. The mixture has no antifreeze protection!
MB approval:
Identification of coolant and corrosion/antifreeze that are approved for use in vehicles/major assemblies of the Mercedes-Benz brand. The application area must be complied with in accordance with Specifications for Operating Fluids sheets 320.1 and 320.2. On the containers for tested products, you can find the term "MB-Freigabe XXX.X" or "MB-Approval XXX.X" as a note.
2. Overview and Specifications for Operating Fluids Sheets
The antifreezes listed in the following Specifications for Operating Fluids sheets guarantee the following important properties:
Ensure heat transfer
Long-term corrosion and cavitation protection for all component parts of the engine cooling system
Long-term compatibility with all component parts of the engine cooling system
Ensure antifreeze protection
Increase boiling point
Resistant against microorganisms
Effective foam suppression
For an overview of the approved Specifications for Operating Fluids sheets for cars and vans, see Specifications for Operating Fluids sheet 320.1.
For an overview of the approved Specifications for Operating Fluids sheets for commercial vehicles and buses, see Specifications for Operating Fluids sheet 320.2.
The following information must be observed:
The products specified in Specifications for Operating Fluids 325.x are antifreezes. They must be mixed with water as per item 3.4 before they are used.
The products specified in Specifications for Operating Fluids 326.x are coolants. They must not be mixed with water.
The products listed in the Specifications for Operating Fluids 325.7/326.7 are not compatible with the products listed in the other Specifications for Operating Fluids sheets.
Fuel cell vehicles require a special coolant for cooling. Coolants for fuel cell vehicles must only be refilled in an F-Cell support point.
3. Mixing Ratio
3.1. Sheets 326.x
The products listed in the Specifications for Operating Fluids 326.x are coolants or finished mixtures and must not be mixed with water. When using them, compliance with the concentration (50/50) must be ensured in addition to the MB approval (see item 5).
3.2. Sheets 325.x
All concentrates or antifreezes listed in sheets 325.x must be used with approx. 50 % by volume of water. This mixing ratio is important for, e.g.:
The freezing point
The boiling point
Heat dissipation
The portion of anti-corrosion protection
The water quality must satisfy the requirements listed in item 3.4. Even with extremely low ambient temperatures, not more than 55 vol.-% antifreeze is to be used. With 55 % by volume of antifreeze, the maximum antifreeze protection, approx. -45 °C, of an aqueous ethylene glycol solution is achieved; a higher antifreeze portion reduces antifreeze protection and heat dissipation in the engine, which can cause irreparable damage. If the coolant contains less than 45% by volume or more than 55% by volume of antifreeze with corrosion inhibitor in the coolant, the mixing ratio must be corrected immediately (see item 5).
Table 1: Target concentration of antifreeze with corrosion inhibitor and water | |||
Sheet No. | 312.0 | 325.0/3/5/6/7 | |
Mixing ratio | Concentrate % by volume | 10 | 50 |
Water % by vol. | 90 | 50 | |
3.3. Sheet 312.0
In special cases (commercial vehicle engines, no antifreeze requirement, see Specifications for Operating Fluids sheet 320.2), coolant additives can be used that are essentially anticorrosion additives. The products must be mixed with 90 % by volume of water. Mixtures of different products as stated in sheet 312.0 are not permitted.
3.4. Water quality
Clean and the softest possible water should be used for processing the coolant. Drinking water often satisfies the 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 there is no available information regarding the water quality or if no suitable water is available, then distilled or deionized water should 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 coolants must be within the limits of table 2.
Table 2: Water quality | |||
Water quality | min | max | |
Earth alkali ions | mmol/l | 2,7 | |
Hardness | °dH | 15 | |
Chloride | mg/l | 80 | |
Chloride + sulfate | mg/l | 160 | |
pH-value | - | 6,5 | 8,0 |
1°dH = 0.1783 mmol/l alkaline earth ions = 7.147 mg/l Ca2+ or 4.336 mg/l Mg2+
4. Ingredients
The coolants and antifreezes with corrosion inhibitor are based on ethylene glycol as the antifreeze component, but differ with regard to the remaining ingredients, e.g. for corrosion protection; see table 3.
Table 3: Specifications for Operating Fluids sheet number and coolant type | ||||
Coolant Sheet no. | Antifreeze with corrosion inhibitor sheet no. | Inhibitors | Free of | |
inorganic | organic | |||
326.0 | 325.0 | Si, B | X | Nitrite, amine, phosphate |
326.3 | 325.3 | X | Nitrite, amine, phosphate, borat, silicate | |
326.5 | 325.5 | SI | X | nitrite, amine, phosphate, borat, 2-ethylhexanoic acid |
326.6 | 325.6 | SI | X | nitrite, amine, phosphate, borat, 2-ethylhexanoic acid |
326.7 | 325.7 | X | Nitrite, amine, borate, silicate | |
5. Monitoring coolant operation
During operation, the corrosion inhibitors of the coolant are consumed and the mixing ratio may change due to water evaporation. It is therefore very important to regularly monitor the coolant if the engine is to run trouble free.
The inspection of the mixing ratio should be conducted with suitable apparatus. To do this, the density or the refractive index can be used to determine this according to Table 4. For individual coolants, the information on the mixing ratio may vary slightly from the values given in Table 4.
If the coolant contains less than 45% by volume or more than 55% by volume of antifreeze with corrosion inhibitor, the mixing ratio must be immediately corrected. The following calculation aid can be used to calculate the top-up quantity.
Table 4: Concentration/antifreeze protection/density/refractive index (approx.) | ||||||||
Concentration | vol % | 20 | 25 | 30 | 35 | 40 | 45 | 50 |
Freezing point | °C | -9 | -12 | -16 | -20 | -25 | -32 | -37 |
Density (20 °C) | g/cm3 | 1,029 | 1,037 | 1,045 | 1,052 | 1,060 | 1,067 | 1,073 |
Refractive index n20° | | 1,355 | 1,360 | 1,366 | 1,371 | 1,376 | 1,382 | 1,387 |
Calculation of coolant quantity to be added for low concentration (Specified: 50 Vol.-%)
Coolant content (total) in liters
Measured concentration in Vol.-%
Computational formula:
(50 - measured concentration) * coolant content / (100 - measured concentration) = top-up quantity for corrosion/antifreeze
Example of calculation:
Coolant content (total) = 8 liters
Measured concentration = 36 Vol.-%
(50 % - 36 %) * 8 l / (100 % - 36 %) = 1.75 liters
This calculated quantity should normally be drained off beforehand
6. Disposal of coolants
The coolants are biologically-degradable material. The statutory regulations or waste water ordinances in each individual country must be observed when disposing of used coolant. It is recommended to have the possibilities available for disposing of materials explained by the local responsible water authorities.
Referenced documents
- bb0040p032001a Specified anti-corrosion protection/antifreeze (Cars, VAN) - Overview
- bb0040p032002a Specified anti-corrosion protection/antifreeze (CV) - Overview