I worked as a contractor for Pennzoil here in Houston, just after the big dust-up between Pennzoil and Texaco. I went back to work for Pennzoil after Shell Lubricants had bought them out (again as a contractor).

Here's the deal - Shell formed a partnership with Texaco and Saudi Aramco in the late 90's. There were several companies formed - Equiva (Trading and Services), Equilon and Motiva. The idea behind this joint venture was to allow the distribution of the Shell/Texaco brands of gasoline by co-locating some of the distribution centers, and refining. As noted in a previous entry in this thread - today, gasoline is virtually a completely homogenous product here in the US. Regular Unleaded and Super Unleaded are refined at a variety of locations and piped to disribution centers all around the country. (Almost no Mid-Grade gas is refined, it's usually produced by blending Regular and Super). With the Equilon / Motiva distribution system, at each distribution center, tankers would fill up with the required base fuel, to which additives specific to the particular brand were added. If the tanker was headed to Shell gas stations, the Shell additive package was added. All of the companies that refine gasoline use the same network of pipelines to distribute their fuel around the country. Some of the lines are "fungible" - which means a refinery say in Deer Park TX which is to deliver XX barrels of Regular Unleaded to a distribution center at a location somewhere along the pipeline can inject those XX barrels into the line, while simultaneously withdrawing the same amount of gasoline at its destination. Other lines require the fuel to actually travel from its injection point to its withdrawal point before being removed. The actual process of tracking the fuel in these type of lines is quite complicated and rather impressive.

Anyway - - - - when Chevron bought Texaco, the SEC required parts of the partnership be dissolved. Shell wound up with the lubricants division of Texaco. Then Shell turns around and purchases Pennzoil, which was primarily a lubricants company, but also owns things like Jiffy-Lube, Quaker-State (via a merger in 2000) and a variety of other automotive-related companies, like Gumout, Rain-X, Fix-a-Flat, Slick 50, Blue Coral, Black Magic, and on and on and on.

So, now Pennzoil, who once hated Texaco (see http://www.agsm.edu.au/~bobm/teaching/MDM/pennzoil.pdf) , is now under the same corporate umbrella of Shell Lubricants. How the wheels of commerce do turn....

The Walmart-branded (Super-Tech?) oil is nothing more than repackaged Pennzoil. Great way to save a few bucks and get some good oil.

My last gig with Shell Lubricants was on the supply-chain side of the organization, so I got to see and hear a lot of goings on about supplying the customer with their product. As previous entries in this thread reveal, people are intensely loyal to their choice of oils. Companies like Shell are very aware of this condition and try to do everything they can not to cause ripples in this pond. When research is done on the matter, the most common reason for individual loyalty to a brand is that a respected person in the past had recommended brand-a or had panned brand-b oils.

POS correctly noted that all oils are required to pass stringent testing as laid down by the SAE (Society of Automotive Engineers). This helps to ensure that when you pick up 10w-40 oil that, regardless of brand, it will perform up to the standards set for 10w-40 oil. Additives are another matter entirely - some oils have a higher level of detergents in them, others less-so. There are a lot of oils being marketed as "high-mileage" or "SUV-specific". From my experience working at the company and being in contact with the marketing folks that push this stuff, there's probably very little difference between a 10w-40 High Mileage oil and "plain old" 10w-40. The average driver will probably sell their current vehicle long before the difference between the two oils is noticed.

Just my $2.50.