[mwr]

Nissan and Infiniti built great transmissions back in the GEN-1 days, but reading that dipstick is not straight forward. And my efforts to figure it all out led me to these conclusions, which I hope will help you DIY owners either flush your transmission fluid yourself, and/or help you communicate with your mechanic who may need some coaching if he never has performed a transmission flush on an FX45 or FX35 in the same way I will explain below:

For a complete summary on how I flushed my 2004 FX45 transmission fluid you should download the attached .pdf file.

Also, I found no issues using Valvoline Max Life ATF (Full Synthetic, which says on the label this fluid is compatible with Nissan's Matic "J" ATF) and you can order this stuff for $18/gallon on Amazon with free delivery. That's 1/4 the price of Nissan's Matic "J" fluid at $18/qt.

However, the real value of this thread is knowing how easy it is to flush your entire transmission fluid; without mixing the new ATF with the old ATF; and you will do that by removing the transmission COOLEER return line; add a 4' clear vinyl tube to a 1-gallon empty jug to catch the old fluid; and then you just start-and-stop your engine every 3 qts of fluid ATF you remove from the tranny pan; and replenish that fluid with new Max Life ATF; then repeat 3x-4x.

You will need to buy at least 3 gallons (12 qts) of Valvoline Max Life ATF for this job. (Your FX35 & 45 Gen-1 trannys hold 10.78 qts.) So I recommend you use 4 gallons (16 qts) to be sure you get a clean flush, and if you find you don't need the 4th gallon then you can always return it later.

Also, IMO, I would not bother changing the metal filter screen since your tranny does not use a paper element filter, and there are good arguements for not changing filers on cars with over 100,000 miles. Plus the whole process is easier and faster when you just leave your old tranny screen-filter "as-is."

Next, you need to learn how to read your dipstick at normal operating temperature; instead of at 149F, because you probably don't own a scan tool that will read transmission fluid temperature? ...But maybe you do? ...If so, the best way to properly fill your FX tranny is to bring the fluid temperature up to 149F and then fill the pan, with the engine running, to the 3/4 point of the hash marks on the dipstick.

Note: Normal operating tranny fluid temp in in the 165F-169F range (with OAT = 80F). (See .pdf file for more information on how to interpret the Infiniti instructions to read the dipstick and/or pay close attention to the pictures I created below.)

It's really important to change your tranny fluid every 80,000 - 100,000 miles. Some shops settle for "diluting" or mixing your old fluid with new fluid, because they have never changed ATF by pulling the transmission cooler return line. And you will find convincing your mechanic to do it this way maybe difficult. ...So do it yourself! ...Or just present them with the .pdf to read and maybe they will thank you for teaching them something new!

4 gallons so Valvoline Max Life ATF is only $80. And once you do this service, I bet you will notice improved throttle response and torque; maybe even better MPG around town! And the process is easy after you remove your engine's bottom (plastic) cover, just like you do when change your oil, and there you will see the 2 transmission cooler (low pressure) hoses. One is "in" and the other is "out."

To know which one to pull, that will depend on if you have an FX45, which means you pull the transmission cooler line on the passenger side; and if you have an FX35, then you should pull the cooler line on the driver side. (Note: It's just a quick release clamp. Easy-peasy!)

See attachments.

 

[mwr]

* Depending on your Infiniti model (and other models for that matter) you should verify which line is the correct transmission cooler return line to remove for draining the ATF out -- or you can remove both lines and drain them both in the bucket. However, you will find that only one line will expel fluid when you start the engine.

 

[mwr]

DON'T OWN A SCAN TOOL THAT CAN READ ATF TEMPERATURE?​

Here's the DIY owner's approach I decided to follow when re-filling the ATF to the proper level on the Infiniti FX dipstick.

* First you need to know what the dipstick fill tube feels like "to the touch" when you reach normal operating temperature (~169F as shown on the charts above).

* To know what I'm taking about, just drive around as normal, for as long as you like, and then touch your dipstick tube.

At this point, your engine water temp will be ~182F to 185F, depending on the OAT, and your tranny fluid temperature will be ~169F. ...and the dipstick tube will be quite hot to the touch. ...And now you know what normal operating temperature feels like! However, I also need to point out, this is NOT the temperature you want to use when measuring your ATF level on the dipstick.

...But please, feel free to check you dipstick at this normal operating temperature so you know how much higher you will find it registering on the stick. Just know, that level could reach into the "first bend" on the stick and maybe higher, which is telling you this is an unreliable region to measure your ATF level. I.e., Infiniti dipsticks are read differently than any other car I have every owned. So don't assume your tranny fluid level should register within the hash marks at normal operating temperatures! (Tell your mechanic too, because they will probably make this mistake!)

* So don't be fooled! Read this post thoroughly and get familiar with the right way to fill your transmission fluid; and the right way to read your dipstick. ...One more thing, your mechanic will probably not want to take the time to use a scan tool. So you may need to convince him to do so. So, that's just one more reason to DIY if you ask me. Plus the entire process I have outlined is easy and think much better than using a traditional transmission ATF exchange pump!

* Don't want to get under your car? ...No problem. But buy a 12V, $18, transfer pump on Amazon to remove the first 4 qts of fluid out of your transmission pan; and then you only need to remove the bottom engine skid cover to reach your transmission cooler lines located next to your radiator to expel your old ATF fluid inside the torque converter, etc. (EASY PEASY!)

12V Transfer pump: Amazon.com: HYDDNice 12V 60W Oil Change Pump Extractor Oil Change Pump Transfer Pump Diesel Fluid Pump Extractor Scavenge Suction Pump for Truck Rv Boat ATV : Automotive

* FYI, I found the difference between the low-hash mark point on the dipsick vs. the high-hash mark on the dipstick is only ~3/8 qts, and this is when the fluid temperature is in the low-warm range (or about 122F).

HOW THE AVERAGE DYI OWNER CAN READ A DIPSTICK WITHOUT A SCAN TOOL​

1) In the morning, when the fluid is cold... start the engine as usual. Let the engine run for 1 minute or so, as normal, and then drive the car for 1-3 city blocks, as normal, and shift through the gears.

2) Find a flat spot on the street or gas station to pull over and then do these things:

* Put put your hand on the dipstick tube (rear passenger side of the engine on my FX45) and note how warm it feels. When it feels warm to the touch, this will indicate your ATF is ~122F. (See charts above for where your ATF should register on the dipstick. ...It should be between the 2 lower notches at this point.

==> Now add 3/8 quart more of ATF and let the engine warm up more.

3) Now drive 5-7 blocks normally. Pull over and touch the dipstick tube again. This time it should feel much warmer, but not too hot to touch. ...This is the 149F point, and as you can see by the charts, your fluid level should rise and will register at the mid or higher-end region within the hash marks.

With the engine running, you will likely spend 5 minutes checking the dipstick several times, and at this point your ATF will continue to heat up, but not that much. When you feel the tube getting a hotter, but not too hot to hold on to, this is the ~149F point.

...And now you want to add ATF (1/8 qt of ATF at a time) ...but only to the top of the hash marks and no higher! ...And you are done!

Note: Your tranny dipstick is extremely sensitive. ...And each time you check the dipstick you should first shift through the gears while pausing for 3 seconds between shifts. ...Then wait 1 minute before you check the fluid level on the stick.

REMEMBER: Reading the dipstick at normal operating temperature (169F+) is not very accurate.

Tip: Use a file to etch a shinny mark on your dipstick to help you see the level and catch fluid.

 

[mwr]

MORE OP TIPS...

SO YOU DON'T HAVE A SCAN TOOL TO MEASURE ATF TEMPERATURE?

Solution: Here's another way to find the 149F ATF temperature point so you can use your dipstick to identify the upper hash mark ATF fill level.

1) Before the first engine start of the day... reach over the passenger side of the fender and touch the ATF fill tube with your hands... and note how it feels to the touch. This is the "feel" of the Outside Air Temperature (OAT)... what ever that is. (Use a 10mm socket to remove the bolt that locks the dipstick in place.)

2) After driving your car for the day... touch the ATF fill tube with your hands again (lightly) and now you know what it feels like when your engine is at normal operating temperature.

NOTE: It will feel pretty hot so only touch the fill tube lightly!

Now you know you know you are looking from some "feel-point" that is about -20F lower than 169F or normal operating ATF temperature.. which is the 149F point we want to find so we can use the dipstick and reach the upper level of the hash marks on the dipstick at this 149F point.

A BETTER WAY TO FIND THE 149F POINT

Swipe a digital meat thermometer out of the kitchen or buy a cheap on on Amazon for $10. Then do this:

1) After you start your car in the morning, drive it normally for about 4-5 miles.

2) Find a flat spot in the road or better still you can pull into a gas station.

3) Then stick the digital thermometer into the ATF fill tube (with the dipsick inserted) and see if you are at 155F after about 2-3 minutes. And if your not at this point... just drive your FX another couple miles more to warm up your ATF to ~155F and recheck the dipstick level.

IMPORTANT: Be sure you shift though the gears... and wait 2 minutes after that... before reading the dipstick.

WHY 155F? I am recommending your elevate the temperature of the ATF fill tube to 155F on the digital thermometer, because the ATF fill tube is metal... and there is radiant heat coming off the engine to consider. That said, the ATF fluid in the pan should be cooler than what the thermometer reads; and I estimate this will be about -5F lower than what the thermometer says.

Again, the goal is to find the 149F point, because that's how Infiniti calibrated the dipstick at the upper fill line of the hash marks.

OTHER CONSIDERATIONS

* That notch on the dipstick is the 120F level, which means the ATF fill tube should feel warm to the touch at this point... and at this temperature you should be able to grab it and old on to it for about 10 seconds without discomfort. Still, this is not a good measuring point.

* Apparently, the design of the transmission pan does not lend it self to checking the fluid level at normal operating temperature of ~169F. So, this is another reason why we need to find the 149F temperature point, because that is what your dipstick is calibrated too.

* When you add ATF you should do so at 1/8 to 1/4 qt increments or you may overfill your system. I also estimate there is only a 3/8-1/2 qt difference between the lower hash marks on the dipstick and the upper limit on the dipstick (149F).

* Remember, too much fluid causes foaming at higher, working temperatures and that's not good for your transmission ATF.

 

[ironfistt]

You mentioned this is done without mixing old and new fluid but your procedure has me thinking this isn’t the case, what am I missing? Also, why not just pull the drain plug? When I replaced my fluid, I also did the filter and it was easy to pull the pan and service it since it was drained. Aside from that, it was cheap too for a new gasket and filter.

Lastly I did this with over 200k on the clock, trans never ran better!

 

[mwr]

Ironfistt: I assure you, when you remove the return hose from the transmission cooler (which is on the passenger side hose for the FX45 or the driver's side return transmission cooler hose for the FX35) you will completely draining all the fluid out of the transmission and torque converter.

Moreover, you will see dirty ATF when you fill your milk jugs up; and you will see an ATF color change when the new fluid has completely replaced the old ATF. At this point you can stop your "purge" and go about the process of filling the fluid to the correct level WHICH IS TEMPERATURE DEPENDENT on the graph shown above. In fact, you may spend more time trying to figure out where the proper fill level is vs. the time it takes to "purge" the old ATF our of your transmission.

Don't forget to shift though the gears (slowly) as you fill those milk jugs; and be sure to keep track of what you take out. Also, you need to drive your car before you confirm your ATF is filled to the proper level.

This procedure will take two people and IMO is the best way and the only way to remove all the old fluid without diluting as you proceed. Remember, your first step is to drain the pan once and then refill it (with ~3qts of the new ATF); and then remove the transmission return rubber hose camp and hose. It's really easy and visible after you remove the engine skid plate.