well lets just start by saying that it is pretty much two 2.3 Honda prelude motors put together to make a v8. same piston size and stroke. so its dependable lol. But anyway back to your question.
It all depends on the gear you run, what kind of driving you do, (city or highway?) With a stock gear your city driving will suffer! (For city I would run a 373) and for (highway driving I would run a 355 gear). Accounting that your motor is stock and running well, With 355s on the highway I would say 24 to 26mpg.
The 4.6 is a great motor! Its been around since 1992 and used in the mustang from 1996 to 2010 the made 2v 3v and some sick 4valves like the 2003/2004 fully forged cobra motor i've seen a few running over 1100hp on a stock short block!! There were a lot of changes through the years on this motor but if you ever rebuild one its so freakin easy!! Best of all no push rods!! :)
The horsepower on the 1988 Mustang was # 90 horsepower 2.3 liter engine # 225 horsepower 5.0 liter engine
5W - 30 ( according to the 2000 Ford Mustang Owner Guide for the 4.6 liter V8 engine )
The 3.8 liter V6 engine has a timing CHAIN
In a 1996 Ford Mustang : The 3.8 liter V6 engine ( if you had a Mustang GT it was the 4.6 liter SOHC , V8 engine )
The 1999 Ford mustang was rated at 190 horsepower for the 3.8 liter engine and 260 horsepower for the 4.6 liter engine
( .050 inch ) - spark plug gap for 1986 Ford Mustang - 5.0 liter engine
In a 2001 Ford Mustang : The 3.8 liter Over Head Valve , V6 engine ( and in the GT version , the 4.6 liter SOHC , V8 engine )
That has the 3.8 liter ( 232 cubic inch ) V6 engine ( unless it is a Mustang GT - that's a 4.6 liter ( 281 cubic inch ) V8 engine
a 400ci engine
No , the 1999 Ford Mustang came with the ( 3.8 liter V6 engine ) or if it was a GT version it came with a 4.6 liter V8 engine Helpfull
A Ford Mustang 4.0 liter V6 engine would be ( 4,000 cubic centimeters )
On your 1994 Ford Mustang with the 3.8 liter V6 engine : The engine oil dipstick is on the drivers side of the engine