Compression Pressure Limit Chart
WARNING: This page is about a different car, the 2003 Ford Thunderbird. However, it is still accessible from the selected car via links, so may be relevant.
Courtesy of FORD MOTOR CO.
If one or more cylinders reads low, squirt approximately one tablespoon of engine oil meeting Ford specification on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.