Got the bug,
No significant difference in my opinion with 5 psig, but it demonstrates better viscosity stability, wow I almost sounded like I knew something. and Roush says 10w30 not 20w50 etc, it bewilders me why people do not follow manufacturer instructions.
RedBarchetta, The valvoline VR-1 is different than the "standard" valvoline it has 1200 ppm of
Zinc/Phosphorous as compared to 800 ppm for the regular valvoline. They have reduced the
zinc/phos since the OEM's feel it damages catalytic converters, needless to say I do not have one on the Cobra.