Hard to shift after MTF change (Mazda 6)

[Nathan]

I have a 2010 Mazda 6 2.5L I just got about 3 months ago. After discovering a lot of dirty and low fluids and seeing how careless the dealership mechanics were, I decided to just change everything myself. I will admit, my transmission probably did not need the fluid changed too badly, but I didn’t see how it could hurt, assuming I did everything correctly. I’m also new to auto repair and would like to learn. With that being said, I made sure I knew exactly what I was doing before attempting this (at least procedure-wise that is).

I bought 80-90W gear oil from the parts store, as was recommended to me by the parts guy and the computer. First thing I noticed when doing this job was how slowly the new fluid poured in. Took me about 15 minutes just to wait for it to all drain through the funnel. Once it was full and starting to pour out a little bit from the fill line, I put the nut back on and tried it out. First, it was like shifting through peanut butter. I thought maybe the fluid needed to be warmed up or I needed to run through my gears a few times before it would smooth out. I was still concerned so I actually ended up driving to a few dealerships who might have a mechanic willing to help me out. They all said I had done it correctly and that was the right fluid, but one from an actual shop told me to try Syncro Shift 2 (75-80W), a much more expensive fluid that still matched my trannys requirements. This had a much better result, but it’s still not as smooth as it should be. If it’s in gear and I flick the shifter, it should fall into the center neutral position relatively easily. Now, it tends to stick a little bit to the side and doesn’t quite fall into place. Shifting into gears is halfway decent though. I was actually wanting the shifter little stiffer though to begin with, which is why I sided with the 80-90W rather than 75-90W, even if the difference was small. I’m wondering if this is normal after a MTF change, or if I just drive it for a few weeks if this problem will go away. Shifting did become very slightly better over time with each fluid but not by much though.

I also read MT-90 Redline works, but Syncro Shift 2 seems to be high quality ($30/3qts) and has the right viscosity and color in comparison to the original tranny fluid. I will be calling the dealership I bought it from tomorrow to see what they recommend, but I’d still like some second opinions.

Thanks!

Topic

[zero]

Just run what the manufacturer recommends. The people that decide such things know way more than rando guy on some internet forum.

[Nathan]

I would, but I have no idea what it actually takes. Everybody I talk to, mechanics, parts guys, the internet, all say any 75-80W or 80-90W will work. My manual doesn’t tell me anything and the internet hasn’t helped much as far as a specifics. In fact, I’m disappointed Mazda has such a lack of information in general. Online and in my manual. Tells me next to nothing about fluids or capacities. I suppose I’ll just have to call a dealer tomorrow and see what they use. Do you think I might have done anything damaging to my transmission because of all this or am I probably safe? There’s been no other abnormal behavior other than a sticky shifter.

[Delwyn Ching]

You should use what your manufacturer recommends from your owner’s manual or you can go to Amsoil.com and enter your make, model, year and engine size. You’ll get the correct type and weight of fluid to use.

[transman304]

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2010 Mazda 6 L4-2.5L
Vehicle » Specifications » Fluid Type Specifications » Manual Transmission/Transaxle » Fluid – M/T
FLUID – M/T
Manual Transaxle Oil

Type API GL-4 or GL-5
Viscosity
All temperatures SAE 75W-90
Above 50°F (10°C) 80W-90

Capacity 3.01 qt (2.85L)

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