Omg folks when the bottle says API SP and for gasoline engines it means you can use it, and its warranty safe. And if that's confusing just buy name brand full synthetics and keep a record. Thats it. Warranty is safe.
The choice of viscosity is based on the environment and operating condition. If its sub freezing consider going light, which these days is the lightest weight on the cap. If its very hot and you tow, you CAN go a grade higher.
It has already been established that you DO NOT violate warranty using the an SP/GF-6 API approved (shield or starburst) oil of any common weight so long as its not lighter than what is stamped on the oil cap.
Further more, many owners manuals mention towing and high speed driving as reasons you may consider a higher weight oil (how many times do folks have to post that line from the Toyota manuals).
Can we stop warning people that they will void their warranty if the cap says 0w-16 and they dare pour 0w-20 or 5w-30 or 0w-30 in there? Sheesh.