Marine Penetrol - What is it really?

The Sailing Life: Thinking of Buying A New Boat?: "An interesting tidbit about Penetrol: If you buy a quart of 'Marine' penetrol it will set you back nearly $13.00. If you go to Home Depot and buy a quart of regular Penetrol, then it's about $7.00. You may think to yourself, 'Hmm, the marine stuff must have something interesting about it.' You'd be wrong. A call to the company that makes Penetrol by Herb garnered the following fact: It's all the same. The line that cans 'marine' Penetrol is exactly the same one canning the standard stuff. What changes? The label. And the price."