Meaningless, irrelevant anecdote follows:
Maybe, BENEATH Raylube! A co-worker of mine worked as a teen-ager in a Guadalupe, CA, service station. Each can of each quart of oil added to each customer's engine was up-ended over a tray, to drain, as the residue from the can was collected.
The population of Guadalupe, at the time, included a large segment of agricultural workers who didn't always have an abundant supply of ready cash to buy motor oil, and other things. A customer might not even have the 79 cents Thrifty Drug (LOVED their radio ad jingle!) list price per quart. When asked if cheaper oil were available, the station attendant would quote a lower price. If that discounted price was still too high, the figure would be scaled down again. This customer-centric negotiation continued until an affordable price was reached for the salvaged oil.
My service station attendant friend grasped the economics of the transaction: WHATEVER the final selling price might have been, it was pure, full, 100 % PROFIT! Thus, every sale was satisfactory and not to be missed on any pricing issue, for the station's bottom line.
EVERY brand and viscosity, of course, existed in the final mix. No matter to the desperate motorists who wanted to keep their vehicles on the road. No Internet then, so no oil threads, minutely dissecting the composition and operational effects of various engine lubricants used.
DISCLAIMER: Regrets if I've posted this story earlier; senility IS cruel!
EDIT: Correcting, the jingle I liked was from Thriftimart, not Thrifty Drug:
EVERY DAYS A SPECIAL DAY AT THRIFTIMART
EVERY DAYS A SPECIAL DAY FOR YOU
WHAT EVER YOU PUT IN YOUR SHOPPING CART
YOU'LL SAVE AND SAVE AT THRIFTIMART...