Differential and Transfer Case Fluid Levels

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May 13, 2024 | 07:22 PM

rna352

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Tuned

Joined: Sep 2019

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From: N. Appalachistan

Differential and Transfer Case Fluid Levels

I'm closing in on 30K miles and at that time I'm planning on changing my driveline fluids.

The service manual states:

- Front diff level should be "within 3mm from" fill plug opening
- Rear diff level (M275) should be "10-15mm below" fill plug opening
- Transfer case level should be "within 10mm below" fill plug opening

Besides the fact that the verbiage is unclear, any ideas on how to achieve these fluid levels? Here are the options I've considered so far:

1) Waste a bunch of time dicking around trying to fab a tiny dipstick
2) Fill by spec volume only
3) Fill to overflow, suck out a guesstimated amount (aka pinky finger test)
4) Fill to overflow, plug it and rock on

May 13, 2024 | 07:46 PM

number9xd

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Joined: Jul 2011

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IMO, you could do the pinky test or, do what I’m sure the majority of people have done for decades, fill til it drips out of fill hole and rock on.

May 13, 2024 | 08:52 PM

OBS460

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Joined: May 2022

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From: Everywhere and nowhere

2qts in the T-case is either right at the fill hole or dripping out. I filled everything til it just started coming out the hole.

May 14, 2024 | 12:30 AM

406f150

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Joined: Jul 2017

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Option 4 is what I just did on my 2017.

May 14, 2024 | 04:33 AM

ATC Crazy

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From: SW VA

Fill 'em til they run out.

May 14, 2024 | 06:21 AM

WXboy

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Joined: Sep 2002

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From: Central KY

Quote:

Originally Posted by number9xd

IMO, you could do the pinky test or, do what I’m sure the majority of people have done for decades, fill til it drips out of fill hole and rock on.

This. ^^^ Been doing it for 25 years with zero issues.

May 14, 2024 | 08:36 AM

BSHORT

Cargo Master

Joined: Mar 2004

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From: CA

If you want to be ocd and do it like the book says, bend a piece of bailing wire into the shape of an L with the short end being 10mm. Then when you need the 3mm, clip off 7mm.

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May 14, 2024 | 10:05 AM

philips

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Joined: Dec 2003

Posts: 488

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From: Indianapolis

This is going to be your minimum or low level, level should be "within Xmm from" fill plug opening. On level ground, fill case till it runs out of opening, stops dripping (within reason). install plug.