Something I feel i HAVE to clear up about transmission servicing.

[Mark S.]

Honestly, I've noticed the 8F35 seems to be sensitive to fluid quality.

Can you be more specific?

Fluid changes more frequent than specified certainly will not hurt.

This depends on the fluid change method. I don't believe these transmissions have a drain plug, so you're either sucking out the old fluid, you're disconnecting lines going to the heat exchanger, or you're taking off the pan. Each of these introduces the possibility of maintenance errors. The least intrusive would be sucking out the old fluid.

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[Dude]

The 8F transmission is the result of a joint R&D effort between Ford and GM. The version GM uses is a 9-spd; Ford felt the ratio between two of the gears was too short, so it deleted one.

That’s just great .. two leaders in quality collaborating together ?
It is what it is

but on the other hand, haven’t read there is longevity data or failure rate data on the 8F just have read opinions and suggestions

 

[Jake10080Guy]

That’s just great .. two leaders in quality collaborating together ?
It is what it is

but on the other hand, haven’t read there is longevity data or failure rate data on the 8F just have read opinions and suggestions

Yeah, it's just that the 8F just tends to shift weird at high rpms. Someone told me it's just the torque reduction programming.

 

[FB71]

Can you be more specific?


This depends on the fluid change method. I don't believe these transmissions have a drain plug, so you're either sucking out the old fluid, you're disconnecting lines going to the heat exchanger, or you're taking off the pan. Each of these introduces the possibility of maintenance errors. The least intrusive would be sucking out the old fluid.

drain plug. Drain and fill.

 

[gatornek]

Per Ford workshop manual; Transmission fluid filter is not a maintenance item. It is only to be replaced during an overhaul.

The filter is buried under the drive chain and sprockets, and requires a complete disassembly of the transmission. It's purpose is to catch large debris, in the event of a significant failure, to protect the pump and valve body.

If you are finding any particle larger than dust in the fluid, you have major issues, and the trans should be overhauled. Most trans filters have very large orifices in the filter media, and are only designed to catch large particles. Trans oil does not have the surfactant additives to keep particles in suspension, like engine oil. Engine oil filters are designed to capture particles in suspension. Trans oil is expected to drop the particles to the bottom of the pan/housing.

Drain and fill of the trans is an acceptable procedure, at more frequent intervals than specified. This refreshes the fluid additives and some of the base oil.

This might be the best summation of a trans change that I've read. Had no idea about the difference with oil, in the way it filters.

 

[Mark S.]

drain plug. Drain and fill.

So you fill it from the bottom? Can you be more specific about the transmission's sensitivity to fluid quality? Are there specific symptoms owners should be looking for?

 

[FB71]

So you fill it from the bottom? Can you be more specific about the transmission's sensitivity to fluid quality? Are there specific symptoms owners should be looking for?

No, that's the drain plug. Fill is done through the vent port at the top.
get vehicle to operating temperature. Remove the air filter, then remove the fluid vent. Fluid id added via the vent port on the transaxle.

Follow this procedure;

1. With the engine running in PARK on a level surface make sure the transmission is at normal operating temperature 85-93° C (185-200° F).

1. With the engine running in PARK, remove the transmission fluid leveling plug.

1. Add clean transmission fluid in increments of 0.25L (0.5 pt) until the transmission fluid is even with the transmission fluid leveling plug hole.
   Use the General Equipment: Funnel
   Material: Motorcraft® MERCON® ULV Automatic Transmission Fluid / XT-12-QULV (WSS-M2C949-A, )

 

[FB71]

So you fill it from the bottom? Can you be more specific about the transmission's sensitivity to fluid quality? Are there specific symptoms owners should be looking for?

And by sensitive to condition, my techs have indicated that the 8F35 is hard on fluid, wearing out its additives faster than expected, due to frictional heat. Symptoms may include harsh engagement/delayed engagement of gears, slippage, and DTCs relative to gear ratio. Vehicles operated in an urban drive cycle environment are more susceptible to premature fluid degradation. A simple drain and fill on an accelerated schedule helps maintain the fluid condition. Interval is variable based on usage. My recommendation for most is 30k.

 

[FB71]

It's the same way with the 6F35. People say with 6F units, their ATF showed very black at the first 30,000 miles.

Now I mean for the 8F.. could this be because it basically shares DNA from the 6F? They have identical gear ratios. Etc

the ULV ATF darkens more quickly than the older LV and Mercon. A slight change in color does not necessarily indicate fluid failure condition.

 

[Bucko]

And by sensitive to condition, my techs have indicated that the 8F35 is hard on fluid, wearing out its additives faster than expected, due to frictional heat. Symptoms may include harsh engagement/delayed engagement of gears, slippage, and DTCs relative to gear ratio. Vehicles operated in an urban drive cycle environment are more susceptible to premature fluid degradation. A simple drain and fill on an accelerated schedule helps maintain the fluid condition. Interval is variable based on usage. My recommendation for most is 30k.

This first sentence alone would have me changing its fluid at at least the 30K point.

 

[Mark S.]

my techs have indicated that the 8F35 is hard on fluid, wearing out its additives faster than expected, due to frictional heat.

Can you give us some idea how your techs determined this? Do they send samples off for analysis?

 

[FB71]

Can you give us some idea how your techs determined this? Do they send samples off for analysis?

No. The symptoms I've already stated. Fluid refresh reduces or clears the symptoms. Fluid analysis is to determine contamination.

 

[Jumbo1953]

Thank God for Mark S. & FB71. You guys rock!

 

[gatornek]

No, that's the drain plug. Fill is done through the vent port at the top.
get vehicle to operating temperature. Remove the air filter, then remove the fluid vent. Fluid id added via the vent port on the transaxle.

Follow this procedure;

1. With the engine running in PARK on a level surface make sure the transmission is at normal operating temperature 85-93° C (185-200° F).
2. With the engine running in PARK, remove the transmission fluid leveling plug.

1. Add clean transmission fluid in increments of 0.25L (0.5 pt) until the transmission fluid is even with the transmission fluid leveling plug hole.
   Use the General Equipment: Funnel
   Material: Motorcraft® MERCON® ULV Automatic Transmission Fluid / XT-12-QULV (WSS-M2C949-A, )

Any idea of what the total amount of fluid should' be? In essence, how much should someone buy if they wanted to drain and fill?

 

[V8 Yankee]

I recently did a drain and fill on my 21 BS OB. The process is easier than I thought. Just make sure you have all the tools and it will take about as long as it takes to change the engine oil and filter. I didn't measure the fluid I drained but I had 5 qts of ULV fluid just in case. After draining I added 4 qrts and let it balance out untill it stopped dripping from the leveling port. I believe a good pint or so drained back out until it stopped dripping. So having 4 qrts on hand would have been enough in my case. Make sure your BS is level on the stands just how it sits on the tires and yours should be same.
I'll do another drain and fill at the next oil change and another after that. Seems like cheap insurance for the long term.

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