[arindamcc]

 I am currently using Royal Purple 01320 Max Automatic Transmission Fluid in my four speed Royal Enfield Pre unit primary chain case but it is very strange that with in 2500 km four clutch case oil seal adapter ( 111888/A ) are failed. Oil seal adapter change is very difficult job. I am attached a picture of oil seal adapter. Is ATF not suitable for oil seal adapter ?
Please suggest me what i can do now, back to 20w40 or ATF.

[cyrusb]

I have been putting engine oil in mine since 2005 with no problems. It is hard to tell what the failure is by your pics. Is the rubber swelling or perishing? Who knows what kind of rubber the manufacturer uses, particularly R.E. Use what R.E recommends, its the safest bet.   

[arindamcc]

The oil seal is bonded with metal adapter plate but in my case all four times they are parted.Oil seal is in good condition but parted from metal plate.

[cyrusb]

It could be a host of things. There may be a tendency to overfill the primary. Try not to do that. I let mine stop dripping from the level hole, too much oil here has no benefit.There only needs to be "some oil" in there.  And lastly, stop the "Lubrication Voodoo" and use what the factory recommends.   If it is dislodging the seal from the carrier perhaps you have a venting problem. It is possible the vent is plugged.   

[arindamcc]

There is no venting or over fill, only suspected things are Royal Enfield spare quality control and Voodoo ATF.
Another thing I forgot to mention that the Sprocket nut oil seal is rubbing with clutch case oil seal adapter.

[cyrusb]

Well, you certainly have a point there about RE quality control. Do you think its possible to beef up the seal mounting method RE uses. Is it just pressed in, or pressed and glued? I know what a bitch that job is so you must be ready to pop, (I know I would be).