Pre-treat the shirt with Dawn dishwashing soap immediately upon taking off the shirt. When you or wife or girlfriend wash it 1 - 5 days later, there will be a lot less oil on the shirt. Dawn is the best for something like this.
You could probably spray it with a household degreaser, like Simple Green or 409 or one of the Orange oil cleaners, but you might discolor the shirt. Test on an inconspicuous spot before treating the whole shirt.
"None are so blind as those who will not see."
"A comedian says funny things. A comic says things funny."
