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FORTEC RX8 80W-140 Differential Oil and Drivetrain Lubricants

FORTEC supplies drivetrain lubricants suited to RX8 differential and gearbox servicing, with grades including RX8 80W-140 differential oil for owners maintaining or upgrading their drivetrain. Use this range to identify the right fluid by grade and application before committing to a service.

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Two angled white RX8 80W-140 gear oil bottles with FORTEC Racing Gear labels

FORTEC Full Synthetic Differential Oil SAE 80W-140 GL-5 (2 x 1L Bottles) for Mazda RX8 (Series 1 & 2, 2003-2012)

Full synthetic GL-5 lubricant in the correct 80W-140 grade for RX8 rear differential servicing. Two 1-litre bottles supply the full service quantity.

$100

Mazda RX8 gearbox oil in two FORTEC Spec R 75W-90 bottles

FORTEC Full Synthetic Gearbox Oil Spec R SAE 75W-90 GL-5 (2 x 1L Bottles) for Mazda RX8 (Series 1 & 2, 2003-2012)

Fresh Mazda RX8 gearbox oil in a two-litre service pack. Full synthetic 75W-90 GL-5 formula for smooth shifts and lasting gearbox protection.

$100

What owners are saying

AUTOEXE Sports Steering Wheel (Red Stitch) for Mazda RX8 (Series 2, 2009-2012) AUTOEXE Sports Steering Wheel (Red Stitch) for Mazda RX8 (Series 2, 2009-2012)

I recently installed AutoExe's Sport Steering Wheel on my ND. Taking my time and watching the various video's a few times, it took me a little over an hour, with no real issues, to install the new wheel. I couldn't be much happier with it. The wheel is extremely well made, at least as nice as OEM, with red stitching that matches my SRC paint nicely. It's a tiny bit smaller in diameter than stock, but much thicker, with a mild D shape for additional leg room. For those considering an improved steering wheel, this is a fabulous option in my opinion, particularly if you have red car.

GENUINE MAZDA OEM Intake Solenoid for Mazda RX8 (Series 1 & 2, 2003-2012) GENUINE MAZDA OEM Intake Solenoid for Mazda RX8 (Series 1 & 2, 2003-2012)

Happy 8's day people! For you series 2 owners, here's the easiest way I found to change these little suckers. RX8 Upgrades providing the genuine goods as always. Remove the air box/ CAI, remove throttle body and remove the top part of the UIM only, this will get you easy access to the solenoids. Now you could remove them from this point, but removing the oil filler neck along with the vacuum chamber the solenoids mount to makes it FAR easier to change them. This whole job can be done in an afternoon for a mechanically minded person. On reassemble, don't forget to place the vacuum reference back onto the bottom of the manifold (has a green check valve) otherwise no valve will work. Reassemble and enjoy. PN is KL01-18-741 for those chasing the part

AUTOEXE Premium Cat-Back Exhaust Muffler for Mazda RX8 (Series 1 & 2, 2003-2012) AUTOEXE Premium Cat-Back Exhaust Muffler for Mazda RX8 (Series 1 & 2, 2003-2012)

Just installed my spanking new Autoexe Stainless Muffler, and here's a short take of my initial impressions: The Autoexe catback is lovely - very unique 2 box design and the tips are the tapered kind (ie cut at an angle) each lasercut with the Autoexe logo. Very nicely polished midpipe which connects beautifully (and easily) with the exhaust outlet. Most importantly, the exhaust tips have a perfect visual alignment, unlike other exhausts i've seen where one tip protrudes out more than the other. The Autoexe definitely doesn't have this problem. Also, the 2 box design has a lower profile than stock. Previously, i used to scrape and even dent the exhaust box when clearing humps or even parking - not so with the Autoexe. The Autoexe performs really well, at least on my AT. There is a noticable increase in low end torque, and the car just feels substantially lighter. Revs are much more responsive, and the slight lag felt when launching the car seems to have melted away. Linear acceleration is also much faster (at least across 1st 3 gears), and i'm reaching 120-130kmh much faster on 2nd gear alone (NB mine is the 4spd AT). I'm very pleased with the low-torque gains on the Autoexe - finally i have that slight 'lurch' from start which the manuals seem to have, but the ATs don't. The Autoexe starts off idle with a really low, bassy growl. When first installed, it was barely audible, but sounds louder now. In time, the db will increase to an extent. On higher RPM revs, exhaust sounds deep and wet, and def not those shrilly Remus' we hear on the expressways from time to time. Installation was a breeze, and took under an hour at Monster Garage at Ubi, who's the only authorized dealer in Singapore, so these guys know their stuff. The torque/hp improvement was a shocker esp on low end, esp when mine's an AT. I've heard of bros installing Fujitsubos and HKSs that have either no or negative benefit. In this respect, I'm mighty pleased with the Autoexe. Sound is not loud, but a soft low bassy growl when idle, which develops into a mature wet sound at higher revs.

Drivetrain fluid condition matters more than many RX8 owners realise. The differential and gearbox work hard in a rear-wheel-drive sports car. As a result, degraded or incorrect lubricant shows up as notchy shifts, increased wear, and inconsistent feel at the limit. FORTEC covers both applications with purpose-graded oils, including RX8 80W-140 differential oil for the rear diff.

Choosing the right grade for your drivetrain

The differential and gearbox are separate systems with different fluid requirements. For example, treating them as interchangeable is one of the more common drivetrain servicing mistakes. The 80W-140 viscosity grade suits the load and temperature demands of the rear differential. Meanwhile, owners researching RX8 75W-90 gearbox oil are looking at a different job entirely. The lighter viscosity reflects the gearbox’s own design requirements.

Selecting your RX8 80W-140 differential oil grade

  • First, confirm which component you are servicing before selecting a grade. Differential and gearbox oils are not interchangeable.
  • Also, check the individual product listing for stated application and grade to match your service need.
  • In addition, cross-reference your vehicle’s service information for recommended fluid type and service interval.
  • Finally, factor in your intended use. A car used at track days or in hotter climates may benefit from fresh fluid at shorter intervals.

FORTEC drivetrain lubricants in Australia

This range brings together FORTEC’s lubricant line-up in one place. Therefore, compare options by grade before ordering. Whether you are planning a full drivetrain service or targeting a single component, review the available RX8 80W-140 differential oil and gearbox oil listings against your requirements.

Learn more about the full FORTEC Lubricants product range on the manufacturer’s official site. However, always check each product listing for application details. Also, use your RX8 service documentation to confirm suitability for your build.

Frequently Asked Questions

What viscosity grade should I use for the RX8 differential?

The RX8 differential typically calls for an 80W-140 grade gear oil. Always cross-reference with your vehicle's service information to confirm the correct specification for your build and intended use before selecting a product.

Is differential oil the same as gearbox oil on the RX8?

No, the RX8 differential and gearbox are separate systems that use different fluids. The differential commonly takes an 80W-140 grade oil, while the gearbox is typically serviced with a 75W-90 grade. Selecting the right fluid for each component is essential - check each product listing's stated application before ordering.

How often should I change the differential oil on my RX8?

Service intervals for the RX8 differential vary depending on use and driving conditions. Refer to your Mazda service documentation for the recommended interval, and factor in your intended use - for example, track use may warrant more frequent changes than regular road driving.

Can I service the differential and gearbox at the same time?

Yes, many RX8 owners plan both services together as part of a drivetrain maintenance session. Just treat them as two separate fluid choices - confirm the correct grade and application for each system individually rather than using the same oil across both.

How do I know which FORTEC differential oil product suits my RX8?

Check the grade and application details on the individual product listing, then compare that against your RX8 service information. The key details to match are the viscosity grade and the intended application - differential versus gearbox - to make sure you are ordering the right fluid for the right component.