r/Cadillac • u/jhoke1017 • 2d ago

How has GM not fixed the 10-speed?

I genuinely don’t understand how this transmission is so bad? I had the dreaded valve body issue, and instead of waiting on a list 3500 deep, I got a full OEM transmission swap as I am still under warranty.

The new one still occasionally lurches when downshifting, and consistently hunts for gears.

How has GM stayed competitive when their transmissions are just….bad? Even my Ford with the same 10 speed is significantly better.

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u/ads1031 2d ago

The best recommendation I can make is to change the transmission fluid. Give it a try.

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u/Extra-Wasabi-8639 2d ago

The service records show it was changed 20k ago. How many miles do you have on yours?

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u/ads1031 2d ago

I change my transmission fluid every 30,000 miles. Since I'm a DIY hobbyist, one "change" actually consists of changing the fluid twice, two weeks apart. I literally just did the first change, the 2nd one is this upcoming weekend.

The partial fluid change I just did did seem to make the transmission shift more slowly, more smoothly. Like engaging the clutch gradually in a manual. I used this fluid, which, despite not being licensed, seems to use the same additive package as the licensed stuff according to this thread. The change didn't seem to affect my 4-cylinder mode vibration (since I have the LGX v6).

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u/Extra-Wasabi-8639 2d ago

Good to know. I was planning to change it often and just have to think of it as regular maintenance for these cars.

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u/upperlowermanagement 1d ago

I had 8 spd rebuilt with the new fluid now it flares on the first shift of the day. Loging shows 18? Psi. I plan to get it tuned. It definitely needs more pressure and shift time decreased