yo Mike!
I use 5W-30
Ford recommended 5W-30 though as shown in this;
Oil, SAE Viscosity Recommendation TSB 98-8-16 by Ford for 89-96
APRIL 26, 1999
ISSUE: Ford Motor Company now recommends SAE 5W-30 viscosity grade forservicing any Ford gasoline-powered vehicle regardless of model year.
ACTION: When servicing any Ford gasoline-powered vehicle, use SAE 5W-30 viscosity grade motor oil. Refer to the following text for further details.
Both SAE 10W-30 and SAE 5W-30 viscosity grade motor oils have been recommended in the past depending on vehicle model and model year.
Tests have proven SAE 5W-30 viscosity grade motor oil provides the optimum protection and benefits for Ford gasoline engines. At both high and low ambient temperature conditions, SAE 5W-30 provides the best overall protection. It allows faster starts under cold ambient temperatures.
SAE 5W-30 also provides approximately 1/2% increase in fuel economy over SAE 10W-30.
SAE 5W-30 viscosity grade motor oils certified for gasoline engines by the American Petroleum Institute (API) should be used for all service procedures requiring replacement of the motor oil.
OTHER APPLICABLE ARTICLES: NONE
WARRANTY STATUS: INFORMATION ONLY
OASIS CODES: 401000, 490000, 499000
Then changed it ti 5W-20 in this later TSB
Oil, Application TSB 02-1-9 for 93-96 Source: by Ford via thedieselstop.com