so I’m looking under neath the car, and I can’t figure out how to top off the diff oil. I’m open to suggestions. Dropping the cage at this point isn’t an option.
Thanx
Mark
The filler plug is item #4 in this illustration
It’s difficult to see under the best of conditions and might be buried under a thick layer of dirt and grease…which should be cleaned away before removing the plug, I might add
Without having the car on a hoist the filler plug can be hard to reach in my experience. However, removing the lower tie plate (itself no 5 minute thing) makes access vastly easier. A bit monotonous and very dirty…14 fasteners I think… but less frustrating in the grand scheme of things.
Others will chime in
Cheers
DD
I was wondering if the tie plate was going to have to come off. My XJ-S was up on the lift and has been for the last 5 years, I poked my head under there and said, Oh no way I’m going to get the center of the diff cover. without taking the plate off… my fear is once it came off it’s going to be a bitch to put back cause things flex and cease to align
I’m sure someone in the forum has some trick up their sleeve
Yes, absolutely there is a trick. The trick is to cut a small (1" or smaller?) hole in the forward bulkhead of the trunk (boot) the same height and adjacent to the differential filler plug to put your tool through to remove the filler plug. This allows easy access to remove the plug to add differential fluid and then reinstall the plug. Then paint the edges of the hole and put a plastic plug in the hole until the next time.
Paul
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Its a bit fiddly but I’ve never had a problem topping up mine. You will need the correct socketry - and a pit or lift will help. This photo of the plug was taken with the car on the ground (no lift or pit).
Frankie
And ALWAYS make sure you can remove the filler plug before the drain plug 
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you wouldn’t by chance have a picture from a farther distance so I can see (locate) where that hole is in relation to the rest of the bulkhead / boot / resting place for the spare tire? I like this idea, though I’m reluctant (Only God know why for) to cut into the car. 
Mark, I can go out to the garage and take a pic- as long as you know I did this to my XJ-SC!
I’m assuming a pump is required. I’ve got a small hand pump from the usual scum bags (harbored Fraught). What are other folks using?
OK, I’ve got 3 XJ-S’s None run of course - Projects for another day. Ugh. but it will be good to know - If it’s not too much trouble. If you’ve got to take the spare out to get to it, then don’t bother. I know what a pain in the ass that can be.
Thank you and thank you for letting me know it’s from an XJ-S.
But thank you for the offer.
Car is hibernating- not too happy to be woken up- but it will get over it.
Hole center is two and a quarter in. up from trunk floor.
Thank you so much @DavetheLimey That is above and beyond the call of duty. Much accolades; and thank you!!
I know exactly where that is
Again, Thank you
Mark
My Dana diff did not have a drain plug, so I drilled upwards until I struck oil, and put one in.
(Just to confuse next owner!)
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Here’s a sequence of photos I put up on the old J-L site.
http://www.jag-lovers.org/snaps/snap_view.php3?id=1356386907
http://www.jag-lovers.org/snaps/snap_view.php3?id=1356388078
Regards,
Andy
2 Likes
It would be a good idea to car wash those places to give a better view.
WalterThank you Andy, I will check it out!
M
Sent from my BlackBerry 10 smartphone on the Verizon Wireless 4G LTE network.
My method was similar to Andy’s, but I found an 8 point socket would fit.
I used a 6 foot long tygon hose and a funnel and poured in the oil straight from the bottle. With some SAE90 gear lube bottles the spout will fit the hose so you can squirt it upwards.
SAE90… I’m using SAE75-140 or that’s what I’ve purchased. Should I return it and get something else? Frankly I’d like to put Amsoil in it but I"m hesitant because of the seals. I don’t know why, they leak anyway… I’ve used it is all of my non LSD with great results.
Al Hastings (May he rest in piece) a buddy of mine swore by it, he sold me on it when talked me into rolling my car down his driveway - engine off clutch in We marked where it stopped in the street. 25’ (feet) from his drive way. Replaced the Diff with Amsoil. it rolled to the 75’ feet. Replaced the Gearbox oil. The car rolled to the next block, over the slight incline and started down the hill. I was impressed.
He and i pulled the head off his Jensen Healey to replace a head gasket. The engine had about 125k on the clock; and the inside looked like it was brand new. Now build up; and he said, “Can you believe that shit! It’s amazing. and I change the oil about every 10k miles!” I miss that ol’ limey coot! He was a good man. Sorry distracted…
I’ll report back tomorrow.
well that doesn’t look too bad, at a glance I poked my head under the XJ-S which has been on the lift for the last 4 years now, and I couldn’t see the diff cover, so I stopped and shook my head; and thought Looks like the pan’s coming off the IRS…
I’ll keep you all posted on my success
Thanx
Mark