[QUOTE=fintstone;12401125]Another guess is they topped off your antifreeze. Anything with 50 50 in the name is often antifreeze. That said, it may have well been an oil supplement.
I went back and looked at my 20K service video and receipts and in addition to the BG Ethanol Fuel System Defender® PN 213 in the gas tank, the Lexus dealer also added BG Advanced Formula Engine Oil Supplement, MOA Extended Life® PN 115 to the oil).
I tried googling 'premium engine conditioner' and it came up with this....
Amazon.com
https://www.amazon.com › Petron-Plus-12121-Engine-...
Nano-monomolecular Technology provides exceptional EP Lubricant protection for metal-to-metal moving parts, engines run cooler, with more power, less fuel consumption, increase in power.