Quaker State by the late 70's had developed a serious reputation in a lot of circles as being a sludge potion. I can personally attest to a few tarred engines being the result of QS.
My understanding, at that time, was that QS was trying to save face by offering this new magic elixer that didn't sludge up. Not only that but make the dubious claim that it was so good you just about never had to change it! Nobody really fell for it, but some of us former QS users had an oil that we could use for regular 3k oil changes and not worry about it sludging up. I only used it a few times and wasn't really impressed due to the price (then, like now, I could get the Havoline a whole lot cheaper) and if I remember correctly it wasn't much cheaper than the M1 was.
I didn't see it again shortly after QS went plastic, around 84 or so.