It might be able to be done with a good conventional base stock, but the amount of VIIs they'd have to add would be huge, and it would likely shear quickly, and the VII package would quite possibly displace some portion of other needed additives.
The negatives outweigh the positives; hence the market does not offer such a product. What can be done and what should be done are two totally different things at times; this is a good example of such.