97 Rear Diff
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Senior Member
Joined: Sep 2003
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From: AZ
97 Rear Diff
I'm planning on changing the fluid on the rear differential of my 1997 F150 4.6 4x4 this weekend and have a few questions I couldn't answer with my manual or a search of the site:
The door code reads "axle 19" and the dogtag on my diff is stamped 3 55 88 6J09...since I did not see "LS" I'm assuming it isn't a limited slip?
My manual calls for 75W90 gear oil and says the capacity is 5.5 pints...less than three quarts? Should I go with Redline 75W90? The speed shop near my house sellls it.
Finally, will RTV sealant around the diff cover work as a sealant or is there also a gasket for the differential?
THANKS
The door code reads "axle 19" and the dogtag on my diff is stamped 3 55 88 6J09...since I did not see "LS" I'm assuming it isn't a limited slip?
My manual calls for 75W90 gear oil and says the capacity is 5.5 pints...less than three quarts? Should I go with Redline 75W90? The speed shop near my house sellls it.
Finally, will RTV sealant around the diff cover work as a sealant or is there also a gasket for the differential?
THANKS
Senior Member
Joined: May 2000
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19 is open, 3.55.....The LS reads like "3 L55". Yes, it doesn't hold all that much. Your gear oil choice sounds excellent to me. I've seen a couple of posts where people searched out gaskets, but most use sealer. Don't use any old silicone. I had excellent results with Loctite RTV ultra grey gasket maker. Good Luck.
Member
Joined: Dec 2003
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I have the same rear end in my 97, but mine says to use 75W140 synthetic on the axle tag. I am going to be changing mine out soon. I have 76,000 on the truck with no problems.
Is the 75W90 for the Limited slip or can it be used in the open rear end also? I don't want to burn it up. I think the lighter oil would be great in my MN winters, especially for short trips. I was considering the Mobil 1 75W140, or should I go with the lighter oil?
Is the 75W90 for the Limited slip or can it be used in the open rear end also? I don't want to burn it up. I think the lighter oil would be great in my MN winters, especially for short trips. I was considering the Mobil 1 75W140, or should I go with the lighter oil?
Senior Member
Joined: May 2000
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Use what the tag says. Both of my F-150s said 75W140 on the tag and one truck says different in the Owner's manual. Your Mobil 1 choice is excellent and it works in LS and open rear ends. If you were switching to the lighter oil for MN winters, you would be using 75W in both of them. They are the same in cold weather.
Technical Article Contributor
Joined: Dec 1997
Posts: 9,417
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From: Windsor,Ontario,Canada
Look up in your manual and it should read part name SAE 75W90 for the front and part number XY-75W90-QL but for the rear is doesn't give the viscosity just a description and the part number F1TZ-19580-B. The 1998 manual gives a description of 75W140 synthetic and the same part number of F1TZ-19580-B. So by reasoning that part number is for synthetic 75W140 oil. Call your dealer and ask about the PN.
Regards
Jean Marc Chartier
Regards
Jean Marc Chartier