🚨 How I RUINED My Mazda CX-9 Transmission with multi vehicle ATF #castrol #valvoline #amsoil #mazda

Product reviewed

• Automatic transmission (ATF) fluid choice for a 2018 Mazda CX-9, comparing:
  • OEM “Mazda FZ” ATF
  • A generic multivehicle ATF replacement: Castrol Transmax (multi-vehicle) ATF (Dexron VI-compatible)

Key points / unique details mentioned

1. Vehicle context

   • The owner bought a 2018 Mazda CX-9 and performed maintenance, including transmission and differential fluids.
   • Mazda claims “lifetime ATF,” but the reviewer argues “lifetime” effectively means within the warranty/service window.

2. Initial dealership fluid substitution (the cause of issues)

   • The dealership did not have Mazda FZ in stock.
   • They replaced it with Castrol Transmax multi-vehicle ATF, which they described as Dexron VI compatible.
   • After this change, the transmission shifting became “jerky.”

3. Tried software/learning fix first

   • The owner attempted a transmission relearn procedure (a manual sequence intended to relearn fluid-related characteristics).
   • It helped briefly (“corrected for the first couple of miles”), but the jerking returned.

4. Research into fluid property mismatch

   • Mazda FZ properties are not clearly published.
   • The closest alternative suggested was Aisin (e.g., AISIN MFZ), implying possible OEM-related formulation differences.
   • Reviewer’s takeaway:
     • Castrol Transmax is significantly different in characteristics such as density/weight, pressure points, flow, and viscosity behavior.
     • Valvoline is described as closer than Castrol, but still not an exact match.

5. Mazda guidance received

   • Mazda’s email guidance stated that if a non-Mazda FZ fluid is used, they recommend:
     • Drain and refill back to Mazda FZ
   • This suggests Mazda views fluid differences as a meaningful cause of shifting issues.

6. Dealership resolution / user experience improvement

   • The dealership was described positively (prompt replies and supportive service).
   • The owner returned for:
     • A full drain and refill using Mazda FZ
     • A relearn
   • After that, shifting was smooth again.
   • The reviewer isn’t certain whether the relearn alone or the exact fluid change was responsible, but concludes the fluid substitution was the root issue.

7. Clear recommendation / warning (major pro/cons)

   • Don’t use generic multi-vehicle ATFs (like Castrol Transmax multi-vehicle) as substitutes for Mazda FZ when Mazda FZ isn’t available locally.
   • If Mazda FZ isn’t in stock: ship/source the correct fluid instead of substituting.
   • The reviewer notes that the jerking might not bother everyone, but they are sensitive to even subtle drivetrain changes.

8. Maintenance interval advice (additional recommendation)

   • The reviewer suggests changing transmission fluid earlier than “lifetime,” roughly:
     • Every 50,000–30,000 km
   • Their own change occurred at 115,000 km (~75,000 miles) after purchase, and they frame earlier changes as better for long-term longevity.

9. Overall product conclusion (OEM vs alternatives)

   • Mazda transmissions are described as built to last when maintained.
   • Despite typically not being “OEM-only,” the reviewer says Mazda FZ is the practical and safest choice for these models.

Pros (about using correct fluid / Mazda FZ)

• Smoother, corrected shifting behavior after switching back to Mazda FZ
• Helps avoid jerky shift complaints attributed (by the reviewer) to incorrect ATF characteristics
• Supports long-term durability when maintained properly

Cons (about Castrol Transmax multi-vehicle ATF substitution)

• Jerky shifting soon after the service
• Fix attempts were only temporary until the fluid was corrected
• Potential for subtle drivetrain feel issues (noticeable to the reviewer)

Comparisons made

• Castrol Transmax multi-vehicle ATF (Dexron VI compatible) vs Mazda FZ
  • Reviewer claims Castrol’s fluid characteristics are quite different
• Valvoline
  • Mentioned as closer than Castrol, but still not the same as Mazda FZ
• Aisin MFZ
  • Mentioned as a likely closest alternative because it may be related to OEM-style formulation (not explicitly confirmed)

Ratings / numerical scores

• No formal ratings (stars, scores, etc.) provided.

Overall verdict / recommendation

Recommendation: Use OEM Mazda FZ ATF for the 2018 Mazda CX-9. Avoid: generic multi-vehicle ATF substitutes like Castrol Transmax multi-vehicle ATF when Mazda FZ isn’t available in-store—instead source/ship the correct Mazda FZ.

• The reviewer’s experience strongly links the non-OEM fluid substitution to jerky shifting, which was resolved after draining/refilling back to Mazda FZ.

Speakers

• Single speaker/reviewer: one person describing the full experience, dealership interaction, Mazda email guidance, and results after switching back to Mazda FZ.