I use the oem cross shaped cruciform seals.
I don't trust the aftermarket design.

 

There is a big oil drain relief groove and hole between the rear main journal and the rms. Oil is pumped out of the rmj, but the groove and hole give it a drain back path in to the pan. There is literally no way for pressure to build behind the rms.







However that same oil that is under pressure at the rmj can be pumped out between the parting line on the sides of the journal, hence the crucifix seals. If you had an oily rms it likely was being pumped out at the parting line and the crank threw it around.

To the poster that said the dealer replaced the rms and solved their problem, I doubt very seriously they dropped the transmission to change the rms and DID NOT replaced the crucifix seals. More likely they did the crucifix seals only and charged you for the rms (much bigger job).

 

That makes sense.
Thanks for explaning that.

 

@Extinct thanks very much, I know in my case they dropped the transmission and replaced the seal. As I trust that mechanic and they investigated the source of the leak and got my ok prior to the work I have to accept their diagnosis. But it is a 14 year old Disco who knows what went on prior to my ownership the seal may have been damaged by someone else and just gave up.

Your explanation and images make it look like a pretty rare failure.

 

https://www.roverparts.com/resources...TEhCQ1ZrIn0%3D

AB video on rear main seal leak: "The main seal on a 4.0 or 4.6 V8 engine is only one point where an oil leak can occur."

 

No, he shows the crucifiorm seals and cam plug as potential leakers too, and they are.

 

"Only one point where they can leak." Not "The Only" point... I read it that way at first too but the video shows all of the ways it can leak.

 

Fixed the wording so it is less confusing.

 

Where does one acquire those older style cruciform seals? Can only find the aftermarket ones.

 

Bearmach has them
I bought 2 sets a couple months ago, about $12 a pair.