Oil viscosity and brand change?..

So in the 410 stroker in the duster I've always used pen grade 15-40 as recommended by the machine shop..
I still have the break-in oil in my 408 stroker in my truck... Both are needing oil changes.. 8 quart and one 6 quarts in the other... Both have solid flat tap it lifters..
Both driven in the summer and kept in the garage... For the most part I no longer drag race the Duster and have put a lot less hotter cam in it yet still has pretty high compression. The truck 408 again is a dish piston pump gas rig for sure..
I'm currently paying at least $10 a quart for oil and I'm looking at the VR1 20-50..
I can get 15 quarts sent to my door for 70 bucks.. said to be the highest zinc oil there is on the market.. (according to the internet....:rolleyes:)
I know I know I'm saving $80 per oil change and it's my cheap insurance but really is it? Am I going to wear out the engine or blow it up or do something like that because I switched? I don't live paranoid and I don't like to think I do super stupid stuff either...
opinions and suggestions welcome..
After all isn't that what the form is for? LOL..