Completely Stolen from someone elses post on another site:
Wal-Mart has gone out on a limb or is having a knee jerk reaction to lastest conformity laws regarding Ultra Low Sulphur Diesel (ULSD).
They are refusing to sell anything that is considered a diesel fuel additive. Problem is, you won't know until you get to the registers and have to jump thru hoops to check out. It's even worse if you're using a "self service" check out.
In addition to Diesel Kleen, Marvel Mystery Oil in the red container or plastic bottle is also effected.
I sent an email inquiry to the folks at Marvel Mystery Oil and received this very prompt reply. FYI- here it is.
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Dear Mr.
Thank you for your interest in Marvel Mystery Oil. Please be assured that Marvel Mystery Oil will soon be back on the shelf at your favorite retailers. Wal-Mart is returning all of their stock in order for us to apply a neck sticker to each bottle. The EPA passed a law in 2001 which required diesel fuel to have no more than 15 ppm (parts per millon) sulfur effective June 1, 2006. Diesel fuel aftermarket products
were never notified that this law also affected them. The law stated that diesel additives had to carry a label stating that they complied with the 15 ppm sulfur or not. We are in the process of relabeling all Marvel Mystery Oil and will be back on the shelf shortly. There is not any wrong with the product in the bottle. This was strickly a labeling issue. If we can be of any further assistance, please let us know.
Sincerely,
Marvel Oil Company, Inc.