Why is wd40 so expensive these days?
WD-40 Multi-Use Product - Multi-Purpose Lubricant with Smart Straw Spray. 11 oz. (12 Pack) by WD-40 $49.88 ($4.16 /can) https://www.amazon.com/WD-40-Multi-Use-Product-Multi-Purpose-Lubricant/dp/B00JIHTCR8/ Recycled oil is not the same thing.
Same reason HC is soooo expensive. .
If you want to make it yourself, you would need to run a sample to use a GCMS. And, if you then find out the ingredients, don't expect to pay the same price for volume at Home Depot that the WD-40 manufacturer gets when it buys the ingredients by a tanker car.
Because a lot of R&D went into its development. Water displacement 40 is made to a very specific formula and not just made up with mixing petrol with old engine ils etc etc