The development of additive packages is absolutely expensive. I once worked with a PhD chemist at XYZ additive supplier on behalf of a customer to do testing for a specialized hydraulic fluid. My customer had to pay $100k up front just for starters in order to have the formulation certified for various end-user requirements. Additional costs arose of course as testing and tweaking proceeded.
We tested the formula on various equipment, peered over various charts of friction tests, examined wear on pump gears, clutches, controls, pistons, seals, particle counts, FFTIR and other analysis. One test showed a weakness in oxidation requirements so we tweaked the formula with a different dual anti-oxidant, retested, and then settled on the final additive mix.
Before it was over, the bill was close to $200,000. That was back in 2005.
I had heard (through the grapevine) that the Dexron VI formula development, with tweaking and testing cost GM over $3 million. I can't vouch for that figure but it sounded about right.
Honestly seems low.
I worked with an additive company on fleet testing PC-11 and doing some lab work / tear downs. Just the one fleet test we did was north of 5 million dollars. Between all the free oil, lab services, paying a fuel stipend, engine tear downs. Covering cheesy warranty issues for the fleet. Doing live on-truck monitoring, including adding sensors. Having trucks only stop at certain places for fuel. They footed the bill for it all.
Supposedly all their PC-11 development came to over 700 million. And that was when I stepped away from that fleet testing aspect.
Add pack development is extremely expensive.