Did AutoZone discontinue VR1 20w-50???...thoughts on Rotella 15w-40

Went to AutoZone the other day and the slot for Valvoline VR1 20w-50 racing oil was gone. They told me it was discontinued but thier website shows it available. Anyone no if its true or if Valvoline discontinued producing it. I was thinking of switching to Shell Rotella 15W-40 anyway. Been running 20w-50 for the last 11 years / 10K miles....Will switching to a thinner oil after this period of time and miles affect anything negatively? I thinking no and I'll probably get a small boost in oil pressure. Insight fellas...
:burnout: