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Guide

Gear Oil – Types, Specifications and Selection Guide

Everything important about manual, automatic, CVT and dual-clutch transmissions: Specifications, viscosities and what to look for when making your selection.

Gear Oil

What is Gear Oil?

Gear oil lubricates gears, bearings and synchronizer rings, dampens shocks, dissipates heat and protects against wear and corrosion. Depending on the transmission type (manual, automatic, CVT, DSG/DCT), formulations and specifications vary greatly.

  • Stable lubricating films under high pressure (EP additives)
  • Thermal and oxidative stability
  • Compatibility with friction pairings (clutches, synchronizers)
  • Cold flow properties and shifting comfort

In Brief

Transmissions are sensitive to incorrect friction values. Use exactly the specification required by the manufacturer.

Transmission Types and Typical Oils

Each transmission type requires its own friction values and specifications.

Manual Transmission

Mostly GL-4/GL-5 oils in 75W-80 / 75W-90 / 80W-90. Pay attention to shifting comfort and synchronizer compatibility.

Automatic (ATF)

Special ATF according to OEM specifications (e.g. Dexron, Mercon, MB 236.x). Friction value stable over lifetime.

CVT

Specific CVT fluids for steel belt or cone pulley CVT. High shear stability, defined friction characteristics.

DSG/DCT

Fluids for wet/dry dual-clutch transmissions. Exact friction values for clutch packs and hydraulics.

Specifications and Approvals

Important standards and manufacturer approvals for gear oils:

  • API GL: GL-4/GL-5 for hypoid gears and axles.
  • OEM: VW G 052/G 060, MB 235.x/236.x, ZF TE-ML, BMW MTF, Honda MTF, Toyota WS, and many more.
  • ATF/CVT/DSG: Dexron, Mercon, MB 236.xx, ZF Lifeguard, JASO and manufacturer-specific approvals.

Pay attention to exact approvals – wrong friction values lead to shifting problems and premature wear.

Tip

For mixed fleets (cars, vans, trucks), an overview of OEM approvals is worthwhile to reduce product variety.

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Maintenance, Intervals and Guidelines

  • Follow change intervals and fill quantities according to OEM.
  • Do not use universal fluids when specific approvals are required.
  • For ATF/CVT/DSG: Strictly follow temperature and fill level specifications.
  • Do not mix different specifications without approval.

Avoid Common Mistakes

  • Wrong API GL class
  • ATF instead of MTF (or vice versa)
  • Non-approved universal oils
  • Wrong fill level/temperature during ATF service

Frequently Asked Questions About Gear Oil

Briefly answered – for workshops and demanding users.

Can I use GL-5 instead of GL-4?
Not always. GL-5 contains stronger EP additives that can affect some synchronizer materials. Check manufacturer approval.
Does ATF never need to be changed?
"Lifetime" fills are often marketing. For heavy-duty use, a change according to manufacturer specifications is recommended.
Are CVT and DSG oils interchangeable?
No. CVT and DSG require completely different friction profiles and additive packages.

Need the Right Gear Oil?

We support you in your selection – for smooth shifting and maximum lifespan.

+49 (0) 2306 91 29 380
info@gtl-gmbh.eu
Warehouse / Dispatch: In den Telgen 4b, 44536 Luenen