Bigdog, the change in price from $22.50 to $36.00 is Valvoline's insurance escrow collection for their new 300,000 mile guarantee.
To me, it says their own faith in their product is not very high. From now on they are collecting a 60% insurance premium on every purchase. Most people probably don't think of their vehicle becoming high mileage until after 125,000 miles has passed and it's too late to register, but they want to use this magical product anyway. Doing so, they make the premium payments, even though they can't collect on the guarantee. Those discovering the guarantee early may begin using the product possibly from only 10,000 miles. Likely they will pay the premium many times over. Registered or not, the faithful will pay the premium multiple times as they use the product over the miles. Also, how many registered users will decide to sell or trade their vehicles early removing them from the pool?
With so many premiums that can be paid with so many exceptions against collection, the odds are well in Valvoline's favor to make this guarantee part of their advertising. It should stimulate many sales.
Nothing that I have opined in any way should suggest that Valvoline's High Mileage Full Synthetic oil is not a good product. I'm only stating my opinion as to why the price would make such a large jump coincident to the 300,000 mile guarantee being made.