Yeah, right, motor oil. Not to change the subject or anything, but has anyone ever noticed the late Sheldon "the infallible" Brown's deadpan sense of humor? I never met him, but I pick it up in his writing sometimes.
Here's what he says about motor oil: "There are probably lots of other liquid oils that would work as well-RAAM pioneer Lon Haldeman uses SAE 30 motor oil, but his saddles tend to wear out after only 300,000 miles or so (according to Cyclist magazine)." Does it sound to you like he's serious? Sounds to me like he's pulling someone's leg.
If you're talking about a new Brooks saddle that you've paid $50 - $200 for, my advice is: leave it alone! Ride it for at least a few hundred miles before you do anything to it.
If you're talking about a 15 year old saddle you've bought used or inherited, it has probably dried out a bit and it could use some Proofide.
This one ++++++ ! I have noticed the same humor injected in his writings, which is exactly how I took this one!!!!! Sometimes he even tells you it's a joke; but, not always...