Mazda6 transmission fluid change

pyroMark

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2010 CX-9 GT AWD ; 2005 Mazda6s GT
Changed the transmission fluid in my 05 Mazda6 s last night.

At 62000 miles I expected it to be a bit dirty, but it was pretty brown. I was surprised because when checking the dip stick and wiping on a white paper towel, it doesn't look too bad, still has some pink color to it. The fluid that came out was definitely more brown and nasty.

I refilled with Castrol Import, Type T-IV compatible. It was about $5 a quart, half the price the dealer wanted for the genuine Mazda stuff. Hope this is OK - anyone have comments on this?

I just did a drain and fill and it was very simple on the 6s.
1. Jack up car.
2. open drain plug - you need a 10mm allen wrench to do this. I used a 10mm allen socket that worked great. It was not on too tight at all (has never been opened). Drain into a container that you can measure how much to put back in - this will save a lot of guess work later. Let the jack down during this process and you might get some more to drain out. I got about 3.5 quarts out - about half the total capacity.
3. Replace drain plug and refill through dipstick. I couldn't find a fill port, I'm sure it has one somewhere, but it definitely is not easy to access/find. Used a long neck funnel and had to lift/angle the funnel a bit to let air out while filling.

I'm planning to do another change in the next couple thousand miles, just to get more of the dirty fluid out. At least the fluid in there is now half as dirty as before - not sure if it all mixes nice.
 
I know of at least one other person who has been using the castrol import and says they've had good results.

Also, I bought my car with about 62,000 miles on it, and the fluid needed to be changed. Place i bought it from changed it for me before I picked it up, fluid was nice and fresh. It had significantly darkened within 10,000 miles, so I started doing a drain and fill with a synthetic. These transmissions run really hot, and I'm hoping the synthetic holds up better. So far so good.

Also, there is a fill-port, but it's hidden beneath the airbox, and when I tried to loosen mine, it was jammed tight and I just ended up partially stripping the torx fitting. So I left it alone and just used the dipstick.
 
I've been using Mobil 1 ATF. When I bought it, it was listed as suitable for T-IV applications, and now it no longer has that on the label. I had to use a bit of Lubeguard black (friction modifier) to get the feel just right. I think Mobil 1 ATF is much closer to Mercon V's friction than T-IV. I used about 1/3 of the amount of Lubeguard black that you would use to convert Mercon V into T-IV, which tells me roughly what the friction properties were.

Now that I've got it dialed in properly, it's performing very well and holding up to the heat much better than the regular T-IV fluid. But I think it was more trouble than it was worth, and I'd look for something else if possible.

I believe some people have had good luck with Redline D4? Frankly, I find it hard to believe that its friction properties are appropriate, as there's no way a fluid can actually work for Mercon V and T-IV. The safest option would be to just use T-IV and change it frequently. The Castrol you used is an appropriate substitute for T-IV, I believe (friction properties close to or even identical to T-IV).
 
I did another drain and fill and accidentally put a bit too much fluid in. I was an inch over the hot full mark.

I thought this would be way overfilled, but it turned out to only be 1/2 quart. I'm surprised that it was so little. It looks like the difference between low fluid and full is only about 1/4 quart. Anyone else notice this?

(measured while hot, but not too hot, engine idling, after driving and running through gears.)
 
That sounds right. The engine oil dipstick is a quart between min and max, I think the transmission dipstick range is a pint.
 
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