Tech Basics

Fluid Situation

A field guide to operating fluids for Mercedes-Benz passenger cars • 1946-2019

Richard Simonds

Club members often contact me with questions about which specific factory-authorized operating fluids they should use in their classic (1994 and older) and contemporary (1995-2019) Mercedes-Benz vehicles. This brief overview will provide answers from current Mercedes-Benz technical references with links to more comprehensive information for those who require more fine-grained detail. Generalizations about all Mercedes-Benz models after a certain date do not apply because federal regulations changed – especially during the transition from leaded to unleaded gasoline and from high-sulfur to low-sulfur diesel fuels. While I include the data that I am aware of, your best option is to refer to either the correct Owner’s Manual for classic vehicles or the Operator’s Manual for contemporary vehicles, that pertains to your specific Mercedes-Benz automobile. This article refers to cars and other consumer vehicles and does not include commercial vans, trucks and heavy equipment. Included are operating fluids that end-users would likely need to know about, but not highly specialized fluids that would only be used by classic-car mechanics or contemporary-car service technicians.

References available online: Mercedes-Benz Factory Approved Service Products – November 2001, MBUSA; and Mercedes-Benz Specifications for Operating Fluids (MB BeVo) – January 2019, Daimler AG. An internet search for “Mercedes-Benz Operating Fluids” will identify links to both these sites.

Fuels

Gasoline: You should use Premium (91-95 Research Octane Number) for all vehicles with the exceptions listed below. Unleaded fuels without a lead-substitute additive may be used in all postwar vehicles as they have hardened valve seats and valves. Do not use any fuel additives. Always use Top Tier gasoline that meets American Society for Testing and Materials’ standard D439 as these include chemicals that inhibit carbon buildup in engines. Never use any gasoline with more than E10 ethanol to avoid voiding the warranty in contemporary vehicles and to avoid even more serious damage to fuel-system components in classic vehicles. In states where it is available, use non-ethanol fuel in your classic vehicles. Otherwise, be sure to have all rubber-based components upgraded to parts that will not be damaged by ethanol: these include hoses from metal fuel lines to other system components and mechanical fuel-pump diaphragms.

You may use Regular Unleaded (87 RON octane or 89 RON blended octane) in the following vehicles:

1946-1955 low-compression engines in the 170 series, the 300 series (300, 300a, b and c), and other early models with low-compression engines – 6:1 to 7:1 compression ratios.

1972-1974 and 1986 190E 2.3, 1975-1985 (per MBUSA) – check the Owner’s Manual for your engine’s specific requirements.

Diesel: You may use Diesel No. 1 (high sulfur with up to 500 ppm) in all pre-1994 vehicles. You must use Diesel No. 2 (low sulfur with up to 50 ppm) in 1994-2006 vehicles and ultra-low sulfur with up to 15 ppm in all 2007 and newer models per ASTM D975 No. 1-D or 2-D. Note: All Diesel No. 2 fuels worldwide are now ultra-low sulfur and may be used in any diesel engine regardless of age. Diesel No. 2 fuel has more energy and higher lubricity than Diesel No. 1. Mercedes-Benz USA requires that you use only commercially available diesel fuels and prohibits biofuels (cooking oils, etc.);  these oils do not have the additives and Cetane ratings to avoid damaging engines. Biofuels absolutely must not be used in any 1994 and newer engines. One disadvantage of Diesel No. 2 fuel is its likelihood of becoming a thickened gel in cold weather because it is not paraffin-based. Refer to the Operator’s Manual or Service Information MBNA 00/007 11-82 for correct cold-weather operation instructions.

Engine oils

Gasoline engines: Engines prior to 1998 should use paraffin-based oils meeting American Petroleum Institute’s specification SH or SJ, such as Castrol GT 10W-40 or 20W-50. These oils have the levels of zinc and phosphate required to meet the needs of tappet engines, camshafts and bearings to avoid premature wear. Synthetic oils that also are rated as API SH or SJ – in addition to the newer designations – may be used, although it is recommended that synthetic oils be used only in engines that have just been rebuilt and have never used paraffin-based oils to avoid leaking around seals. Engines from 1998 to 2019 must use synthetic oils that meet M-B specifications 229.1-229.5, with API specifications SL, 2001-2004; SM, 2005-2010; and SN, 2010-2019.

Diesel engines: Engines prior to 1994 with up to 500 ppm fuels should use oils that meet API specification CH-4, also usable with CG-4, CF-4, CE and CD specifications. Engines using low-sulfur diesel fuels with up to 50 ppm must use API CI-4 engine oils in engines from 1994-2006. For engines using ultra-low sulfur diesel with 15 ppm fuels, API specification CJ-4 should be used in engines built from 2007. Any engine can use oil that has the appropriate API certifications on its label for that model engine. If you have any question about the oil to use in your model, check your Operator’s Manual; requirements can be different from the federal standard based upon the state where your vehicle was originally sold.

Coolants

Mercedes-Benz has updated its MB anticorrosion/antifreeze part number from BQ 1 03 0002 to MB anticorrosion/antifreeze AGENT part No. BQ 1 03 0004 for 2015 and older vehicles and to part No. BQ 1 03 0005 for 2016 and newer vehicles. The company’s advice: “Caution! The use of aluminum components in M-B engines requires that anti-corrosive/anti-freeze specifically formulated to protect aluminum parts be used. Failure to use MB anti-corrosive/anti-freeze may result in a significantly shortened service life. While there may be a number of products available that will provide the required protection, all such products have not been tested for Mercedes-Benz vehicles. The above product is suitable for our engines and can be mixed with the original anti-corrosive/anti-freeze filled in at the factory.”

Brake fluids

All Mercedes-Benz vehicles in the United States use DOT 4 Plus brake fluid, listed on MB Specifications sheet 330.1, MB part No. 000 989 08 07 10 (0.75 liter) or 11 (5.0 liter). Because brake fluid is hydrophilic, it absorbs water and must be changed every two years to avoid corrosion to the master and wheel cylinders. At the same time, the clutch fluid must be changed every two years to avoid corrosion to clutch master and slave cylinders; use the DOT 4 Plus brake fluid.

I have seen brake and clutch systems where the fluid had not been changed in well more than two years; the fluid is filled with metal particles and the cylinders are so badly pitted that fluid leaks around the seals, leaving the driver with no brakes or clutch function. It is dangerous to drive and expensive to replace all the cylinders and internal components.

Air conditioning

R12 Freon was used in automotive air conditioning from the 1950s until 1993. Because Freon was found to be a contributor to atmospheric-ozone depletion, it was banned in all types of cooling systems (commercial, home and automotive); R134a refrigerant became standard in 1994. If you have a classic Mercedes-Benz that has Freon air conditioning, it can be converted to use R134a refrigerant. But it is not inexpensive and it does not have the same cooling power, though it is good for our common environment.

Lubrication products

The list of lubrication products in the Mercedes-Benz Specifications for Operating Fluids includes 159 items. Most of these are for use by technicians or mechanics, so I will describe the few that are most relevant to the owner who will have servicing done by a Mercedes-Benz dealer or an independent technician or mechanic. Do-it-yourself owners can find all the lubricants, fluids, greases, special oils, pastes and service products necessary to maintain the classic, young-timer and contemporary Mercedes-Benz.

Listed are a few lubrication products that may be of use to general owners.

Automatic transmission fluid: MB Automatic Transmission Fluid – MB Part No. 001 989 21 03 10.

Power steering fluid: MB Power Steering Fluid – MB Part No. 000 989 20 03 10, or use Dextron-III ATF for automatic transmissions and power steering. Note that different part numbers are listed for different models, so be sure to specify your model if purchasing this at the parts counter from your local Mercedes-Benz dealer or through the Mercedes-Benz Classic Center USA.

Manual transmission fluid or gear oil: Different mechanics and technicians have different opinions about whether to use automatic transmission fluid or transmission gear oil in manual transmissions. Both work, although ATF seems to provide better lubrication for the synchronizer in 1946-1990s manual transmissions. However, if bearing noise is detected mechanics will typically recommend using 80-90 weight transmission gear oil.

Mercedes-Benz recommends the following fluid for the few 5- and 6-speed transmissions offered on C- and SLK-Class vehicles: MB Manual Transmission Fluid – MB Part No. 000 989 26 03 (5-speed) and 001 989 26 03 (6-speed).

Batteries

Let’s not forget something that is not an operating fluid, but might need to be replaced by an owner: the battery.

Some classic-car batteries are available through Mercedes-Benz Classic Center in Irvine, California, particularly if you want to show your classic in concours d’elegance events without point deductions for using a non-original battery. Purists can order original-type VARTA batteries in black cases with screw-on battery caps to have the totally original appearance. Interstate now offers some black-case batteries from Germany. If you order a battery for a classic, be sure to specify whether you have the long- or regular-size battery (e.g., W186/W188/W189 300-series, W108/W109/W111 series, etc.) from the 1950s-1970s.

In closing

Operating fluids are the lifeblood of your Mercedes-Benz. Monitoring fluid levels on a regular basis and replenishing fluid reservoirs when required – with the correct product for your specific automobile – is the simplest and most effective preventative maintenance a keen owner can perform. There is no better way to ensure that you will enjoy many years of trouble-free ownership of your Mercedes-Benz. Fill ’er up!