A friend of mine had a similar question earlier this year, mostly about how powerful 493 was after the oil conversion, as he heard UP 4014's oil conversion had increased its tractive effort. I brought his question here to the forum, and the conclusion was that it wouldn't increase the tractive effort. Later on, he told me after talking with D&S museum curator Jeff Ellingson that it had increased 493s tractive effort. Don't know what to think of it myself, sounds like Russ489 is more knowledgeable about the subject,
"493 performed well and precisely as expected as far as tonnage capacity"