Mazda5 Transmission started slipping while on a road trip

I'm in the middle of a road trip from Cleveland Ohio to Pawtucket Rhode Island in my 2008 Mazda5. Drove over 600 miles with no issues. Then the last 50 miles I noticed the trans began downshifting not just on hills but even normal road inclines and I had to accelerate harder to get up to speed. The roads were level until about the last 150 miles traveling through the Berkshires with many up and down grades. Plus its been 90 degrees. No dash lights. I checked the fluid level and it seems full, even over-filled. Fluid isn't black on the district and doesn't smell burned. I just bought the car a few weeks ago and am wondering if the used car dealer put in the wrong fluid? Wondering if I do a drain and fill by disconnecting the line at the cooler to get all the fluid out including from the torque converter and refill with fresh correct type fluid, if that might resolve the problem...at least to allow me to drive home 650 miles?
 

ricksmz5

Contributor
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2010 Mazda5
I was the 2nd owner of a 2010 Mazda 5. Had 90,000 miles on it when I bought it. Fluid was grey. Owner's manual implies you never have to change the fluid! I drained mine- w/o taking any of the cooler apart- and added three quarts of new fluid. That brought the level close to correct. Did that a couple more times over a year, and then the last time, drained and added 3 quarts of Royal Purple Transmax ($50). After you get the plastic undercarriage shield off, it's just as easy as an engine oil change.
 
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Thanks for the reply. I understand the procedure but was wondering if that fluid change would hopefully correct the problem long enough for me to drive home and have it thoroughly gone over.
 
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2010 Mazda 5 Sport
Man, I feel for you but no one knows if it'll help or hurt. It could do either or neither.

If the fluid looks good but you suspect it's the wrong type, then maybe a full flush could help. Just replacing a few quarts probably won't.

Doing anything at this point may terminate what little is left :(

Best bet may be to drive it back and just pray.

Not a fun spot.
 
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Man, I feel for you but no one knows if it'll help or hurt. It could do either or neither.

If the fluid looks good but you suspect it's the wrong type, then maybe a full flush could help. Just replacing a few quarts probably won't.

Doing anything at this point may terminate what little is left :(

Best bet may be to drive it back and just pray.

Not a fun spot.
I'm wondering if I do a full drain and pump out of the torque converter from the oil cooler line until the fluid runs pink and shortfill by a quart to leave room for a full bottle of Lucas Antislip additive, if that might restore enough to drive 650 miles most of which would be at a constant speed of around 65-70mph. So the trans won't have to do muck work and stay in 5th gear.
 
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2015 Mazda 5 Sport
There is also the possibility of TCM overheating. Check the forum. All Mazda 3 and Mazda 5 before the skyactiv have such issue. It takes me about two hours to relocate the TCM module.
 
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