Transmission Fluid Level- Park Vs Neutral

[Matt]

So it's been evident for a while that the trans dipstick says to check the fluid level in Neutral while the FSM clearly says to fill in Park. There's been discussions ranging from "it doesn't matter" to "it has to be in Neutral" to "it has to be in Park".

Well, since none of us are Mopar engineers, I figured I might as well go right to the source and try to get an official response.

I'll keep updating this first post with the responses. You'll see from my response today I'm expecting to get my inquiry moved up to a more technical/official representative...


Dear Matthew:

Thank you for contacting the Jeep Customer Assistance Center regarding
your inquiry on how to properly check the transmission fluid in your
2007 Commander.

The torque converter fills in both the P (PARK) and N (NEUTRAL)
positions. Place the selector lever in P (PARK) to be sure that the
fluid level check is accurate. The engine should be running at idle
speed for at least one minute, with the vehicle on level ground. At
normal operating temperature (approximately 82 C. or 180 F.), the fluid
level is correct if it is in the HOT region (cross-hatched area) on the
oil level indicator. The fluid level will be approximately at the upper
COLD hole of the dipstick at 70° F fluid temperature.

Be sure that the referenced dipstick is a factory dipstick and not an
aftermarket part added by previous owners.

Thanks again for your email.
Sincerely,
Tony


Tony,

Thanks for the response but I'm looking for a bit more clarification. I have both the OEM factory service manual and the complete 2007 Parts Manuals.

The dipstick is indeed the correct OEM part, 53013686AD. Being a 2007 model year I figured there would be a new revision to the dipstick, but as far as i can see that part number is still valid and has not been superseded.

Although the torque converter fills in both P and N, other XK and WK owners have reported that the levels measured are different. Hence the issue that most people are filling their transmissions based on what the dipstick says (Neutral), whereas the factory service manual clearly says to measure while the vehicle is in Park.

I'm surprised there hasn't been either a rev to the dipstick or a TSB issued to clarify the discrepancy yet.

Other than stating whats in the manual, can you verify that there will not be any transmission damage caused by being under/over filled if the fluid level is checked while in Neutral per the dipstick instructions?

Thanks,
Matt

Latest Reply....


Matthew:

Thank you for your email reply.

The best way to check your transmission fluid is by placing the gear
selector lever in P (PARK) to be sure that the fluid level check is
accurate. The N (Neutrtal) position is less accurate of a reading. The
dipstick will have markings listed to determine whether the fluid level
is within specification.

Thanks again for your emails.
Sincerely,
Tony

For the record, I just got home from running some errands and checked my trans fluid via both methods and the Neutral reading was higher.
When in Park: Fluid level just below the H in "HOT"
When in Neutral: Fluid level at the T in "HOT"

Both were within spec so I'm not worried. I'll probably use "P" from now on and just fill to 25-50% range of the HOT zone.

[lekmedm]

I bet someone like Robby on the other forum could come up with a good explanation for the difference in readings.

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[Matt]

I'm sure someone with internal transmission knowledge could, but that's not why I created the thread. This is more of an "end user FYI" for people doing their maintenance. All past discussions i've found on the topic end without a resolution on the actual OEM recommended way to check the fluid.

If I had to guess, I'd say it has more to do with torque converter pressures fluctuating slightly with engine RPMs. In Park the RPM is more steady (for the most part) than in Neutral.

[lekmedm]

I would agree with that assessment.

My feelings, though, are that the difference in measurements is minimal and inconsequential where the health of the transmission is concerned.

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[Matt]

Exactly.... I dont want to rebuild a trans because ive been using an "incorrect" measuring method..... even if its a screw up from Chrysler in terms of dipstick markings.

[07JeepXK]

I just spoke to my older brother who work at a transmission shop and has a lot of experience with the 545RFE and he said it really doesn't matter if you do it in park or neutral. He said if you have the correct amount of fluid in the trans either method will still fall in the cross hatches on the dip stick.

I have always went by the dipstick and checked it in neutral and never had an issue and have almost 126,000 miles on my XK. I'd personally rather go with what the dip stick says than an owner manual that has been known to have misprinted info in it.

[Matt]

He said if you have the correct amount of fluid in the trans either method will still fall in the cross hatches on the dip stick..

Yeah thats pretty much what I found. In N my fluid level went higher, but still within range.


I'd personally rather go with what the dip stick says than an owner manual that has been known to have misprinted info in it.
Well its 3 source vs 1 now. The owners manual, the factory service manual, and a CSR representative all say the dipstick is "wrong" and the "correct" method per Chrysler is to use Park. I'm amazed that they haven't updated the dipstick yet.

Only way I can really see using Neutral being an issue is if you fill it on the "low" side. Since I found the N reading to be higher, you may end up slightly under-filled.