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Transmission oils for motor vehicles by ADDINOL

ADDINOL automotive transmission oils offer a reliable solution for almost any application. These include high-load hypoid transmission, synchronised and unsynchronised manual and steering transmission, transmissions for hybrid cars, electric cars as well as distribution transmission of car, truck, tractor, forestry and construction machines as well as stationary plant.

Transmission oils from ADDINOL can fulfil even the most extreme requirements and specifications. They offer effective protection against wear and even ideal friction behaviour for cold starts. In addition, our transmission oils provide optimum viscosity, at both low and high temperatures. For example, our Multi Transmission Fluid 75 W 80 or our transmission oils of the GH series ensure the maximum lifetime for your transmission.

Transmission oils by viscosity

If you already know which viscosity class your transmission oil should have, you can discover the categories in detail.

Transmission oils by OEM

We have compiled the approved ADDINOL transmission oils and prepared them for some OEMs.

Your benefits at a glance: 

  • Excellent flow properties
  • Optimised friction behaviour
  • Suitable for the highest loads at high and low temperatures
  • Reliable protection against wear and corrosion for the longest transmission lifetime
  • Increased oil changing intervals
  • Maximum energy efficiency through safe and reliable lubrication
  • Excellent, personal service thanks to our Application Technology
Classic six-speed manual transmission of an Audi
Classic six-speed manual transmission (Audi)

Information about transmission oils

Requirements for transmission oils

The lubrication of a transmission places special demands on the lubricant used. When loaded tooth flanks mesh together, a high pressure acts on the lubricant, which must constantly form a lubricating film in order to avoid direct contact of these friction partners. If the metal surfaces of the tooth flanks meet directly, a friction condition (mixed friction) could occur in which the tooth surfaces may be damaged severely by increased wear. This could result in damage that might lead to the failure of a gearbox. Transmission oils shall prevent this.

The most important requirements for transmission oils are:

  • Lubrication of the friction partners
  • Compatibility with sealing materials
  • Optimised friction behaviour for shifting operations
  • Cooling of the transmission by heat transfer to the housing
  • Protection against corrosion, wear, deposits and foam
  • Optimised viscosity for high temperature and low temperature flowability
  • Resistance to ageing due to oxidation and temperature variations

Transmission oils are required in almost all motor vehicles. There are transmission oils for cars, trucks, tractors and motorcycles. In many vehicles, you might find several different types of transmission. Manual transmissions, differentials, or axle drives – each requires special lubricants. In addition, there is the distinction between lubricants for manual transmissions and lubricants for different types of automatic transmissions.

Open transmission of a sports car
Open transmission of a sports car

Composition of transmission oils

Like engine oils, transmission oils consist of base oils (mineral or synthetic) and additive combinations tailored to the particular demands in the field. The manufacturing process of a transmission oil is basically the same as that of other automotive oils. In comparison to engine oils, however, the additive content can be significantly higher, since transmission oils in commercial vehicles are intended to be changed at intervals of up to 750,000 km.

The application of EP additives is very important for transmission oils. They prevent scuffing of the metal-to-metal friction partners. Axle drives require a high portion of EP additives, which usually consist of phosphorus and sulphur components. However, sulphur components can cause corrosion and ageing problems, so corrosion inhibitors and antioxidants must be added as compensation. A simple example like this already shows that additives in lubricants have to be matched carefully to each other. This requires experience and tests by the lubricant manufacturer in order to find an optimal interaction of the additives in the oil. However, overdosing due to the addition of additives to finished fluids by end users can quickly reverse the advantages of a specifically tailored transmission oil.

In addition, transmission oils have to resist high and low temperatures, prevent corrosion and remove impurities from the oil circuit.

Important additives in transmission oils are:

  • EP additives (Extreme Pressure - to protect against scuffing)
  • AW additives (Anti Wear - to protect against wear)
  • Friction modifier (not always the lowest, but an optimal friction coefficient is important)
  • Defoamer (reduction of foam formation)
  • Corrosion inhibitors (reduction of corrosion and neutralisation of acids)
  • Viscosity-Index improver (optimisation of viscosity-temperature behaviour)
  • Pour Point Depressant (improvement of low temperature behaviour)
  • Antioxidants (reduction of oil ageing)

Automatic Transmission Fluids - ATFs

In Europe, about 35% of all passenger cars and more than 50% worldwide are equipped with automatic transmissions with an upward trend. Modern automatic transmissions are efficient and sporty - largely independent of the design principle. A distinction is made here between three systems, each of which has its own advantages and disadvantages and puts special demands on the fluids. There are torque converter automatic transmissions (AT - most widely used), dual clutch transmissions (DCT - also common and increasingly popular) and continuously variable transmissions (CVT - small market share, more popular in Asia). Learn more about Automatic Transmission Fluids here.

Automatic transmission shifting system of a passenger car
Typical automatic transmission shifting system

Top up transmission oil

Similar to engine oil, transmission oil can lose volume due to constant load or leakage. If the oil level in the transmission unit drops too low, inadequate lubrication occurs, which promotes wear and corrosion in the transmission unit.

Oil level measurement in a gearbox is not always possible without problems. Manual gearboxes usually do not have an oil dipstick. The oil is filled in by the manufacturer and normally only needs to be changed when repairs to the gearbox become necessary. However, if your gearbox makes noises or is stuck regularly, it is worth having it checked by a workshop. These can be signs of additive degradation. However, it may also indicate a low oil level. In this case, the oil level can be replenished before long-term damage occurs. If necessary, a problem that led to a drop in the oil level can also be solved. If a car loses transmission oil, this may be due to the following causes:

  • Defective sealing rings on the clutch side (oil escapes between engine and transmission housing)
  • Leakage at the oil drain plug, filler plug or housing seal (oil leaks from the drive or cardan shaft)

Automatic transmissions often have an oil dipstick. Where this can be found is given in the operating manual. If your car is not equipped with an oil dipstick, the level can possibly be checked via an electronic device. We do not recommend manual testing in a sealed gearbox. This is a complicated process that requires good craftsmanship. In this case, have the oil level checked by a workshop, e.g. during the annual inspection.

If you have an oil dipstick for your gearbox, you can read the level as on the engine. Pull out the dipstick, clean it and re-insert it. Afterwards you can recognize the level by the marking. If the oil level in the transmission unit is actually too low, top up the suitable transmission oil in small quantities. Check the oil level again and again until the desired quantity is in the transmission unit. Too much oil should not be filled either, as the oil pressure will then no longer be correct. Draining the transmission oil is also quite complicated.

Repair of an automatic transmission (CVT)
Repair of an automatic transmission (CVT)

Change transmission oil

Oil changes may also be necessary for automotive transmissions. Depending on the manufacturer, so-called lifetime fillings are designed for an average service life of the vehicle of around 80,000 to 150,000 km. Certain transmission types require shorter intervals (e.g. 60,000 km for dual clutch transmissions). However, passenger cars often achieve the double or the triple of this mileage. Especially for trucks with change intervals of 150,000 to 750,000 km for transmission oils, several oil changes will be necessary during the lifetime of the vehicle. Even for cars that do not reach such mileages so quickly, it is advisable to change the transmission oil every six to eight years, since base oils and additives can be subject to ageing effects due to regularly changing ambient conditions. The transmission oil may change its viscosity after a long period of use and will then no longer build up the required lubricating film. It no longer dissipates heat sufficiently or can no longer build up required pressures. Thermal stress or condensation can lead to additive degradation, which in turn can cause unpleasant shifting behaviour. Just have the oil level in the transmission checked regularly, especially for older cars. A rough guide value for the change interval of a transmission oil is about 80,000 kilometres. Follow the instructions in your operating manual.

Of course, it is possible to change the transmission oil yourself. However, this is much more expensive than changing the engine oil. The process requires appropriate tools (oil change device and lifting platform), specialist knowledge and craftsmanship. Some gearboxes, for example, have to be removed for a change. We therefore recommend that you have the transmission oil change carried out in a garage. There are two possibilities:

  1. Drain the transmission oil and fill in the fresh oil. The disadvantage is that waste oil remains in the nested structure of the gearbox and pollutants remain in the gearbox. However, the variant is less complex and less expensive.
  2. The complete dismantling of the gearbox including the complete removal of the waste oil by flushing. The variant is expensive because it is time-consuming, but much more thorough.

The costs for the complete change of the transmission oil vary depending on the vehicle type. In any case, the process is cheaper than the purchase of a new gearbox if it is damaged by inadequate lubrication.

What happens if transmission oil gets into the engine?

Carelessness may cause transmission oil to be filled accidentally when refilling engine oil. That is not optimal, but also not a reason to panic. As described, transmission oil is similar in composition to engine oil. Due to the different viscosity level and additives, however, it is not recommended to run an engine with transmission oil for a longer period of time. To prevent engine damage or impairment of exhaust after-treatment, a car repair shop should be visited promptly and an oil change carried out. However, if you are forced to drive with the transmission oil in the engine, there will be no imminent danger to the engine. Especially not if the proportion of transmission oil in the engine is only at about 10-20%. Longer distances should be avoided nevertheless.

Dispose of transmission oil

If you carry out a transmission oil change yourself, you will also have to take care of the professional disposal of the waste oil. The same regulations apply to transmission oils as to engine oils. Collect the waste oil in a shatterproof container. Bring it back to the seller free of charge (make sure you keep the receipt for it). The seller is legally obliged to accept the waste oil in the same quantity as sold. Although this regulation also applies to online trading, the customers usually bear the costs of returning the waste oil. Parcel service providers usually classify oil as dangerous goods, which makes shipping cumbersome and expensive. Smaller quantities of waste oil can also be disposed of at the local recycling centres or at some petrol stations. Check with the operator to see if there are any costs. Under no circumstances should you dump the old transmission oil into the household waste or the environment. If oil gets into the groundwater, thousands of litres of clean drinking water will be contaminated. There is a risk of damage to human and animal health. Anyone who is caught disposing of waste oil improperly must also expect high fines. If you have the transmission oil changed by a garage, you will not have to worry about disposing. The garage is responsable to collect the waste oil for professional disposal.


Christian Retschke

Head of Research and Development

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