what oil viscosity is used for 1986 5.0?

I'm gonna have to ask how many miles you have on the engine or the car in general, what viscosity you are currently using and how it's running now?

I live in Florida and have used 10W30 blend and have not had any problems. Oh yea, I have 107,350 miles on it too. Oil pressure is best with a Ford oil filter.

I used 10w30 in the one I had.if I remember correctly that's what it called for.

i use Valvoline racing full synthetic 20w50 and have had a few enginge malfunctions lost oil pump twice drove over 10 miles full throttle and overheated 3 times over 300 and even drove 75 miles on 300°+ temps and no oil or crank issues at all.

I like synthetic oil myself. I live in Florida so there is no need of conventional oils since it doesnt get snow or cold below 30°¡! I have a 95 MIT's 3000 and 198,000 works fine for me.

The car and engine have 632 miles. I have had it stored and covered since new. Kevin