Not to hijack the post but is anyone using Joe Gibbs 20-50 semi synthetic? Do you like it?

Brad Penn IS the old Kendall GT-1. That being said, I use Vavoline 20w-50 as it's readily available.

Beyond engine tear down and inspection, the only true way to tell how well any motor oil is protecting your engine is with: Used Oil Analysis - link

The Used Oil Analysis (UOA) transcends marketing hype and what the “dealer” will tell you.

The lab results from the UOA will show actual wear materials from your engine in parts per million, e.g.

WEAR METALS (PPM)
iron
chromium
nickel
aluminum
copper
lead
tin
cadmium
silver
vanadium

By comparing multiple UOAs, one can determine what brand/viscosity/type of motor oil works best in their specific application.

Where one oil works great in one application, may not work best in another.

When comparing brand/viscosity/types of motor oils, run the same oil through at least two oil change intervals (oil changes) before gathering your used oil lab sample and sending it off for analysis. Doing so prevents possible cross contamination of two different oils and makes for a more meaningful lab report and motor oil comparison.

Until we could trend some UOA results to see how the various motor oils are actually performing in real world conditions, all we will have is recommendations based on personal preference and marketing hype.

We have used AMSOIL for years in our off shore boats .have tried other oils but found nothing better at any price ...you try holding wide open throttle at 7500 rpm for an hour or more without letting off....I now use it in my cars..