From the Amsoil site:
1998 LINCOLN MARK VIII 4.6L 8-cyl Engine Code V 32-valve
FILTERS
Oil Filter........ EAO11 AMSOIL Ea Oil Filter
Engine Oil
Grade 1......API*
100% Synthetic 0W-20 Motor Oil
SAE 5W-20 XL Synthetic Motor Oil
Series 2000 Synthetic 0w30 Motor Oil
All Temps......5W-20[1]1. Use Ford part no. XO-5W20-QSP or equivalent
motor oil meeting Ford specification WSS-M2C153-H.
1996 LINCOLN MARK VIII 4.6L 8-cyl Engine Code V 32-valve
FILTERS
Oil Filter........ EAO11 AMSOIL Ea Oil Filter
LUBRICANTS & FLUIDS
Engine Oil
Grade 1......API*
100% Synthetic 0W-20 Motor Oil
SAE 5W-20 XL Synthetic Motor Oil
Series 2000 Synthetic 0w30 Motor Oil
All Temps......5W-20[1]1. Use Ford part no. XO-5W20-QSP or equivalent
motor oil meeting Ford specification WSS-M2C153-H.
2005 INFINITI G35 3.5L 6-cyl Engine Code VQ35DE
FILTERS
Oil Filter........ EAO12 AMSOIL Ea Oil Filter
Air Filter........ EAA74 AMSOIL Ea Air Filter
LUBRICANTS & FLUIDS
Engine Oil
Grade 1......API*
Series 2000 Synthetic 0w30 Motor Oil
SAE 5w30 Synthetic Motor Oil
SAE 5w30 XL Synthetic Motor Oil
Above 0°F......10W-30, 10W-40
All Temps......5w30[1]1. SAE 5w30 is preferred.
I'd go with the new 0W20 for the gas mileage savings for the Lincolns along with the EaO oil filters for a yearly change, and go with the recommended 5W30 and EaO and EaA filter for the Infinity. Should also save some gas money.