Nissan Repair: Leaky Oil Seal, engine crankshaft, nissan frontier

Question
Thank you so much for your prompt reply to my question. Could the crankshaft itself be the culprit like if it was scored from a piece of dirt or sand getting in there? I have an appointment at the dealer April 4 for them to take care of this under the 60,000 mile drive train warranty. They have already ordered the parts. Is there anything else I should recommend them to look for? I don't like to tell them how to do their job as no one likes that advice. Thank you again. Have a great weekend!

Followup To
Question -
I have a 2003 Nissan Frontier SE 4x4 Pickup that I bought brand new. After only 12,000 miles the engine crankshaft rear oil seal was leaking. Dealer replaced it under warranty. Now some 40,000 miles later it is leaking again which they will replace under warranty. What is making the seal go bad? Is this just going to happen again? Thank you.
Answer -
Joe,

The install of the replacement seal could have been done wrong.  But, I would check the engine for compression loss.  If the engine has excessive loss of compression it could overcome the PCV system and that could be helping the rear seal to go out this soon.

Answer
If the crank was bent or gouged the seal would not have lasted as long.  My bet is the rings are going or the seal was installed incorrectly or damaged when it was installed.  If there was end play in the crank it would have destroyed the thrust bearing long before now...