1998 Club Wagon - according to my owners manual if the rear axle is filled with synthetic lubricant it is considered lubricated for life and do not need to be changed unless serviced - the question I have - how do you know if you have synthetic fluid in the axle - also how can you tell what kind of axle you have - a Ford conventional or a Dana axle - thanks guys - Joe

 

The VIN tag on the driver door jamb has an axle code. There are also visual guides online based on the shape of the rear cover. One of the diff cover bolts should have a tag with gear ratio. Missing on our van. FWIW a Clubwagon likely has a Ford axle unless it’s a Diesel or spec’d for unusually heavy duty use.

Replace the fluid if you don’t know when it was last done even if it’s a claimed lifetime fill. Manufacturers that claimed lifetime ATF fill in the late ‘90s and early ‘00s have walked back such claims and recommend periodic changes. Your axle might have had a leak or drawn water through the vent. Mind the fluid spec if you have LSD.

Sixto
07 E350 5.4 195K miles

 

Actually it is the other way around, a standard cargo or passenger van will have a Dana axle(Dana 60 in a late model van like this), while a cab & chassis truck with an aftermarked box or utility bed on the back usually has a heavier Ford axle... often with duallies.

 

Your 98 axle came with the synthetic 75-90 or synthetic 75-140 from the factory
All of them after about 1996 were filled with the more expensive synthetic gear oil

 

mech007, do you buy into lifetime fluid or is 25 years too long of a lifetime?

Sixto
07 E350 5.4 195K miles

 

Lifetime fluid? Yes sir,
Within reason
If you live in flatland where the temp stays pleasant, the fluid does last about forever, like FL
If you live in AK, UT, WY or CO not so much
If you dunk the axle ever, like launching a boat, I change it or at least pull the cover plate and inspect it every few years (means change)
Fluid is cheap, pinion bearings are not, is my philosophy
So, check the fluid once in a while and check the vent once in a while
That vent needs to be up by the frame or engine compartment for the front axle and free and clear

 

The severe service police and taxi is the service schedule you should all be using IMO
That schedule cuts the intervals roughly in half and adds some services last I heard
Just use your head
If I start draining brand new fluid, I hesitate and consider putting the plug right back in

 

If it has a drain plug

About 10k miles ago I set to change diff fluid. I didn’t know about lifetime synthetic and lifetime fluids claims don’t resonate with me. To reduce the mess, I used an extractor to get as much fluid as possible through a hose into the fill hole. I shoved the hose as far down as it would go. The first couple of ounces was absolutely clean so I poured it back in and found something else to do after checking the vent.

Sixto
07 E350 5.4 195K miles

 

Right, give it another look in 100k more miles

 

Ok, once again half truths and misinformation, lets get this cleared up. There are Ford axles and then there are Dana axles, the diagrams in your owners manual have to be used in unison when determining what gear oil to put in your axle housing. I have posted diagrams from the Ford 1998 E350 owners manual as part of this rant.

The first box under "application" contains the "Ford" conventional axle and or the traction lock with an 8.8" or 9.75" ring gear.
The second lists the "Dana 60" with a 9.75" diameter ring gear.
The third box lists the "dana 70 U" series with a 10.5" ring gear.
The fourth box lists the "Dana 70 HD" series with a 10.5" ring gear.
The fifth and last box lists the "Dana 80" with an 11.25" ring gear.

Please take note where it states "REFER TO FOOTNOTE #4" regardless of which axle is in your truck.


All of these are different axles that were used in different vehicles. We know you dont have a ford conventional axle, and the Dana 80 was only ever used in the E-450 trucks. The E-350 and others recieved either the Dana 60 or the heavier Dana 70 depending on the year and model.

We can X the Dana 80 because you dont have an E-450 with a Dana 80. We can can X the conventional ford axle with the tiny 8.8 ring gear because your not driving a mustang or thunderbird.
That takes the Dana 80 and the Ford conventional axles off the table.

Based on the footnotes number 4, the only portion we are concerned with at this point is... (Dana axles on E-350 vans/wagons with 4.10:1 ratio require Motorcraft SAE 75W140 Synthetic Rear Axle Lubricant.)



That sentence is telling you that if your axle is a "Dana 80, or a "Ford" or "Dana" axle of any type "WITH 4:10 GEARS" it requires the synthetic gear oil SAE 75W140. However if you read the last portion of the footnote 4 it clearly states, "Dana" conventional axles and Limited slip axles require SAE 80W90 gear oil. Its saying that all Dana axles that do not have 4:10 gears require 80W90 gear oil NOT 75W140 synthetic.

WIth that said, people need to start getting the BOM numbers off of the axle tag itself, or start cleaning the rust off the axle tube where the BOM number is also stamped. You cant rely on random people on internet forums for accurate factual information. In your case if you learn to decipher what you are reading, footnote 4 is telling you to run 75W140 _ "ONLY"_ if your truck has a Dana or Ford axle with "4:10 gears", however if you finish reading the footnote 4, It clearly states "Dana" conventional and limited slip axles are to use 80W90 gear oil combined with friction modifier. Got that? Its saying if you dont have a Dana or Ford axle with 4:10 gears you are to be using 80W90 gear oil with friction modifier. Keep in mind this is specifically for your truck which is a 1998. My truck is a 2005 with a Dana 70HD axle with limited slip, however it requires the use of 75W140 synthetic gear oil and modifier.

The internet being what it is, combined with fords history of back stepping on certain criteria years after the fact, your best option is to just call ford yourself when it comes to certain information like this. However without that tag information their likely to laugh at you and hang up.

Is it going to make a hill of beans difference which gear oil you run? Highly unlikely IMO as long as you dont forget to add the friction modifier.

 

Thanks for the feed back - appreciate it - Joe