meh, its just the viscosity rating
I never use that Lucas heavy duty stabilizer for instance in a 4cylinder or what not, meant for racing engines with looser tolerance not kia 4 cylinders IMO
that said, if you use 5w-20 you can go up to 5w-30 if your vehicle is running more than 140Kmiles...
smart
dont trust the internet if you ask me. or the ATF even.....who lurk on here
btw, you ever come to/through Atlanta? if so we can work something out
here is the amazon add for it
https://www.amazon.com/Hogue-Extreme-4-Inch-Tumble-G-Mascus/dp/B003YMASTE/ref=sr_1_fkmr0_1?s=sporting-goods&ie=UTF8&qid=1509749591&sr=1-1-fkmr0&keywords=hogue+automatic+knives+g10