10R80 Mercon ULV vs Mercon LV

[FordBroncoVWJeta]

This is just a cautionary tale of using the wrong stuff.

2024 Ford Police Interceptor Utility (Explorer) 3.3L

This is my work car and it definitely gets its legs stretched on a usual shift. I'm at 60K and in the last few thousand miles the transmission started making some occasional weird shifts. Took it into the local Ford dealer and they couldn't replicate the issue. I wasn't surprised due to how randomly occasional these shifts were. I got the car back and had a couple immediate weird shifts followed by it shifting normal again. I'm guessing they cleared the transmission learning.

We usually don't do Transmission services on our cars but for this vehicle this time around I pushed for it. We had 3 2019 Tahoe's prior to this and between them we went through 3 transmissions, with mine needing another prior to it being sold. Most covered under warranty but lead to a long down time for these cars.

Had the local municipality shop work on the Explorer, change the transmission fluid and filter. After getting it back, I noticed something was immediately wrong. Gear shifts felt fine but a horrible grinding/squealing noise now accompanied the all the shifts. It would get somewhat better after highway driving but it obviously wasn't right. Took it back to the shop and figured out they used Mercon LV instead of Mercon ULV. Its now at an actual transmission shop waiting to get 16 quarts of Amsoil ULV pushed through it. Hopefully this didn't hurt the transmission too much...

I'm surprised how how intolerant these transmissions are between LV and ULV. DO NOT USE THE LV.

 

[meep]

Agreed. I tried a D/F with LV fluid and it didn’t take well at all. It did do very well with about 2/3 ULV, 1/3LV, and 25% dose of lubegaurd red, plus adaptives reset. I know that sounds awfully specific but I was chasing down a problem and the dealer was useless.

 

[bullwinkle]

The 10R80 has an incredibly soft,weak valve body-I’ve had 3 company Transits with 10R80s and NONE of them have shifted correctly nor smoothly once they hit 25,000 miles or so. If I was crazy enough to own a 10R80 equipped vehicle, I would be putting a Next Gen valve body in it yesterday!

 

[ctechbob]

The 10R80 has an incredibly soft,weak valve body-I’ve had 3 company Transits with 10R80s and NONE of them have shifted correctly nor smoothly once they hit 25,000 miles or so. If I was crazy enough to own a 10R80 equipped vehicle, I would be putting a Next Gen valve body in it yesterday!

Early changes and LG Platinum really make a difference in keeping the VB's happy. Once they start to get contaminated it is usually a downhill slope ending in a rebuild.

I've also never heard of a 10R making noise after a change. I think something else is probably not quite right.

 

[FordBroncoVWJeta]

I've also never heard of a 10R making noise after a change. I think something else is probably not quite right.

I assume it was due to the thicker LV. Mechanic said everything else checked out. I did not myself check his work.

 

[ctechbob]

I assume it was due to the thicker LV. Mechanic said everything else checked out. I did not myself check his work.

If I had to guess it was either severely underfilled, or overfilled. When you overfill a 10R it will foam the fluid go into a thermal runaway and cause all kinds of goofy things. Slow shifts, bad flares, etc.

Either that or it was underfilled and the pump was sucking air. That could possibly go away after the fluid heated up and expanded.

It isn't necessarily an LV thing. Yes, you should use ULV in the 10R's, but most of them will operate decently on LV, although not ideal, and not noisy.

 

[FordBroncoVWJeta]

If I had to guess it was either severely underfilled, or overfilled. When you overfill a 10R it will foam the fluid go into a thermal runaway and cause all kinds of goofy things. Slow shifts, bad flares, etc.

Either that or it was underfilled and the pump was sucking air. That could possibly go away after the fluid heated up and expanded.

It isn't necessarily an LV thing. Yes, you should use ULV in the 10R's, but most of them will operate decently on LV, although not ideal, and not noisy.

Ill have to ask the transmission shop when I pick it up if it was over/underfilled.

With it making doing the weird noises while it was cold. Makes me wonder if it wasn't underfilled. I just immediately blamed the LV but your reasoning makes sense.