According to Ford, the problem was from wear in the bore of the pressure relief valve in the oil pump. The wear was agrivated from heavier than intended oil.
I saw SEVERAL of these as a Ford service manager in the early and mid 90s. The latest one I saw was in a 99 Sable with the Duratec V6 (part of the Ford modular engine family as is the Mark VIII engine and 4.6 SOHC engines). Ford had a TSB about it with the part nuimber for the new oil pump that was more resistant to wear from thicker oil (for the 4.6 SOHC).
I was even instructed to have some of the police fleets that we serviced bring in their cars to change the pump without waiting for failure because Ford was aware that they were using 10W30 oil. Some dummy (my reps words, not mine) at Ford had given them a letter saying that 10W30 oil was OK so they didn't need to stock two types of oil.
The TSB still stressed using 5W30, with verbage to the effect that the new pump was more resistant to relief bore wear when heavier oil had to be used.
I saw SEVERAL of these as a Ford service manager in the early and mid 90s. The latest one I saw was in a 99 Sable with the Duratec V6 (part of the Ford modular engine family as is the Mark VIII engine and 4.6 SOHC engines). Ford had a TSB about it with the part nuimber for the new oil pump that was more resistant to wear from thicker oil (for the 4.6 SOHC).
I was even instructed to have some of the police fleets that we serviced bring in their cars to change the pump without waiting for failure because Ford was aware that they were using 10W30 oil. Some dummy (my reps words, not mine) at Ford had given them a letter saying that 10W30 oil was OK so they didn't need to stock two types of oil.
The TSB still stressed using 5W30, with verbage to the effect that the new pump was more resistant to relief bore wear when heavier oil had to be used.