Hi all, this is my first post. I recently purchased a 1997 Landcruiser and also recently switched the motor oil from the Valvoline 5w30 that the original owner opted for and went with Mobil 1 15w50. I swear by synthetics and use them in my 4Runner which has over 200,000 miles now and is still running strong. One strange thing though that I observed is slightly less power with the synthetic in the motor. Can anyone explain why this would be? Would thicker oil rob some horsepower if it were synthetic as opposed to dino oil? Would a thinner synthetic oil be a better decision? Do I just need to wait for a while for the motor to adjust to the synthetic? Any advice at all is appreciated. Thank You.