I am the new owner of a D4 7U. I changed the oil and used Rotella 15- 40 Diesel oil. I operated the dozer for about an hour and noticed a large oil leak that looks like it is coming from around the clutch housing. Could this be because I used detergent oil and it loosened crud and now this caused a leak? If I used another oil would this help? Thanks for any help. Joe..
 

I would isolate the source of the leak. Is it coming from the drain plug hole? Dry clutch? Oil Clutch? Seen some leaks that actually came from the oil pan/main spring.
Everyone has their favorite brand of engine oil. Non-detergent oils are hard to source in California. Many opinions.
Shoot us a photo if you can.
It is possible that the spiral seal is worn and allowing engine oil to migrate into the housing too. JM

its possible. but any oil will do that to differing degrees simply by wetting it with warm oil it will loosen deposits which happens naturally as you run it.
but these were made for a detergent oil anyway. diesel oils are detergent oils. and just becuase you used shell rotella means nothing rotella and rimula are there diesel/heavy equipment product ranges. there is several different oil with different performance and viscosity ratings. and many of them do overlap somewhat.

if you like shell oil contact their tech advice service for a recommendation of which shell products to use.

there is many variables
is this a dry clutch or oil clutch machine.
is the sump gasket sealing properly or is it loose/or simply deteriorated.
is it oil residue draining out the bell housing now that its got warm
did the engine or transmission oil levels change. remember they are checked with main engine at idle, trans in neutral. could it be overfull?
is the crank/rear bore worn and needs building up and machining back to spec so oil is simply weeping past. they rely on centrifugal forces to push the oil back into the motor. never did seal that well.
are the main bearings worn allowing the crank seal to wear