Synthetic Oil Improvement in /6

I use $1.89 house brand farm and fleet or autozone oil in wifes crv going on 195k pulled valve cover and clean as Can be with changes every 7,500 to 8k miles. My dakota 4.7 usually gets whatever name brand is on sale with rottela 10/30 every summer and she has 215k changed every 5k, clean as can be. Did use mobile one on the dakota from about 10k to about 35k and noticed no difference so I must be the odd guy that doesn't think it does a whole lot. My demon gets 10/30 VR1