The best transmission oil for your Infiniti G35 is the fluid specified by Infiniti for your exact transmission type and model year. For most G35s with the 5-speed automatic, Nissan/Infiniti ATF Matic-S is the primary recommendation; Dexron VI is a commonly accepted substitute if Matic-S isn’t available. For manuals, use a GL-4 gear oil such as 75W-90. Always confirm with your owner’s manual or a dealer for your precise configuration.
The Infiniti G35 was produced with two main transmissions depending on year and trim: a 5-speed automatic (RE5R05A) and a 6-speed manual. Fluid choice depends on the transmission type, not just the year. This article outlines the recommended fluids by transmission type and offers practical substitutions, along with buying and maintenance tips.
Identify your G35 transmission
The simplest way to determine the correct fluid is to confirm your transmission type. Check the owner's manual, VIN, or a transmission badge/stamp. Most 2003–2006 G35 sedans and coupes use the RE5R05A 5-speed automatic, while some later models offered a 6-speed manual in sport packages.
Automatic vs manual differences
Automatics use ATF; manuals use gear oil. The 5AT RE5R05A typically uses ATF Matic-S as the primary specification, with Dexron VI commonly accepted as a substitute in many markets. The 6MT uses GL-4 gear oil, typically 75W-90.
Best fluids for the automatic transmission (5AT RE5R05A)
Below are the commonly accepted options for the 5-speed automatic, keeping in mind OEM specs and practical substitutions. Always verify against your owner's manual and local dealer notes, since specs can vary by year and market.
- Nissan/Infiniti ATF Matic-S (OEM specification for many G35 automatics). Use this as the primary choice if you can source it.
- Dexron VI (widely compatible and a common substitute when Matic-S is unavailable). Check your manual or consult a shop to ensure compatibility with your specific RE5R05A revision.
- Avoid Type F and older Dexron II/III formulations unless explicitly approved in your manual; select fluids that state compatibility with Japanese automaker ATF standards.
When filling or topping up, avoid mixing fluids from different OEM specs if possible. If a partial drain is performed, flush or complete drain and replace with a single spec fluid.
Best fluids for the manual transmission (6MT)
The 6-speed manual transmissions in some G35s require a conventional gear oil rather than ATF. Use a GL-4 gear oil, typically 75W-90, and avoid GL-5 formulations that can harm brass components within the manual trans. Some owners prefer synthetic GL-4 75W-90 for smoother shifts and better wear protection.
Why GL-4 matters
GL-4 gear oils are designed to protect brass and synchronizer components inside a manual transmission. GL-5 formulations can be too harsh for these parts and may cause wear or shifting issues over time.
- 75W-90 GL-4 gear oil (synthetic or conventional, depending on preference).
- Common brand examples: Mobil 1 Full Synthetic Gear Oil 75W-90, Red Line MT-90 (GL-4/GL-4+). Ensure the product is explicitly marked GL-4.
- Avoid GL-5 gear oils in older manual transmissions unless the manufacturer explicitly specifies GL-5 compatibility.
Always check your build year’s manual for any drain/fill specifics, as early G35 6MTs may have slightly different requirements.
Additional tips and considerations
Beyond selecting the right fluid, consider the transmission’s condition. If you’re approaching higher miles or experiencing shifting issues, a proper drain-and-fill or professional flush can help. Replacing any transmission filters (where applicable) and gaskets during a fluid change can prevent leaks and extend life. Use a clean environment and avoid mixing old and new fluids in ways that contaminate the system.
Summary
The best transmission oil for an Infiniti G35 is the fluid specified in your owner’s manual for your particular transmission type. For most G35 automatics, Nissan/Infiniti ATF Matic-S is the primary recommendation, with Dexron VI as a widely accepted substitute if Matic-S isn’t available. For manuals, use a GL-4 75W-90 gear oil. Always verify the exact specification for your vehicle’s year and market, and consult a dealer or qualified technician if you’re unsure.