A 1995 4.6L V8 Thunderbird uses 5W30 or 5W20 engine oil. You can use Castrol Syntec, Mobil 1, Valvoline, Motorcraft, or Royal Purple engine oil. Try to use a full synthetic engine oil. However, it is a matter of preference of oil with some owners.
The Ford modular engine was originally introduced back in 1991 in the Lincoln Town Car applications as the 4.6L Romeo SOHC engine, though it wasn’t until 1996 that it replaced the venerable 5.0L (Windsor) in the Mustang, and in 1997 in the F-series. The first 4.6L engines built were produced in Romeo, Michigan beginning in 1991. Most Romeo blocks are marked with an "R" in the block.
In recent news from Ford, the 5.0 V8-powered Mustang GT will return for 2014. A hacked-together 2015 Mustang prototype was recently spotted as well. An EcoBoost four-cylinder engine will be added to the Mustang lineup. Ford is planning an independent rear suspension (IRS) setup for the next-generation Mustang. The only factory Mustang to ever ride on an independent rear suspension was the SVT Cobra model that was produced between 1999 and 2004.