John Deere sells a product called "corn head grease", which is used to stop/slow the leakage of oil past seals on gearboxes. They have had this product for years, so I would expect that there is some validity to its claims.

Before you go putting non standard lubricants in your final drives to hide an oil leak keep in mind that there are no gears on the entire machine that take as much abuse as the final drives. Using the wrong lubricant can cause catastrophic failure that can render the entire machine uneconomical to repair. Some members on this forum who ran these all the time found there are better lubricants than even Cat recommended but I am pretty sure they did not go to corn head grease or similar products.
The seal will be a bellows type seal. As far as I know there is no seal adjustment per se but you can adjust the bearing as pointed out which may solve the oil leak if your lucky but most likely it will be a split in the bellows or a damaged sealing face. No longer available from Cat but you can still get them elsewhere..

cat even published info on how to repair those bellows seals.. another member posted this info ages ago. i downloaded copies of it at the time, not sure where i saved it though.

Give me a # for the bellows seal. I just so happen to have spent the last week digging through an old CAT parts stash where there are various bellows seals still in the boxes. I haven't finished (by far) cataloging this stash of parts but I have seen other bellows I have not listed yet. This is all old stuff. I do have 3B5751 (2ea.). I know that some others are in the "can't find the #s pile of boxes".

According to page 168 of the ACMOC library's D8 14A parts book the # is 7H2199.
Craig

My parts books for the 14A and 15A are all saying 5H428. 7H2199 are the input shaft or pinion shaft seals between the clutch drum flange and bearing

3B5751 is bellows seal for 2T D4, 6G thirty/R4, etc.

Nice catch Phil, I was looking at part 1 at the top of pg.168, part 2 at the bottom of the pg. shows 5H428 (5H0428). I thought the drawing looked wrong but in my rush to go to lunch I used it. 
I'm sorry,
Craig

Hello All
I found some very important information from edb (or Eddie B whom we greatly miss). He talks about changes made to the seals due to damage caused by too thick oil.

Hi Rick,
the little seals on the pins I am sure are just to hold the bellows in place during assembly of the F/Drive and sprocket etc.
From memory they are made from flat rubber sheet and could be punched out using wad punches, they do not seal any thing, just hold, if I recall correctly the rings are only on 3 of the 6 pins.
The numbers you cited in your last post would just be die numbers from the maker.
My D8 Serv. Man. tells me that the later seals have 6 pins, older ones had 3, and to drill 3 extra holes to accomadate the extra pins. I seem to recall this as in cold weather with thick oil the 3 pins could shear off. I would suggest putting the 3 pin units in the outer hubs where they are easy to get at if problems occur later--don't have to pull sprocket. At the Dealer we normally used to put all new seal units behind the sprockets for this reason. Good Insurance.
When fitting the sprocket or outer bearing housing coat the cork seal faces with moly grease to prevent the facing adhering to the metal facing plate--if the cork is dry it can adhere to the face and tear, this also can occur when the tractors have not moved for some time.

As for the taper on the seal face just glue the cork seal on with the special Cat Contact Cement (5H2471) for the job, have done many this way without the tapered former, the taper is built into the face of the bellows. Carefully align the seal and press firmly into place with the fingers going round and around several times checking to ensure full glued contact.
When glued and dry rotate the new seal face on a large sheet of sand paper or such to get a full witness mark of the seal face around the outer edge of the facing to about 1/16" width minimum for the thinnest witness width.
Hope you can follow this ramble.
Cheers,
Eddie B.

Hi, PhilC.
Good catch. Thanks for sharing.

Just my 0.02.