I was wondering if you guys had any tips for getting better gas mileage.I have an 88 5.0 with 200,000 miles.I replaced the cap rotor spark plugs and wires and air filter and fuel filter. I am getting about 10 miles to a gallon.this is a stock truck with stock tires and country road driving

 

At 200K change the oil and consider running a quality additive to improve seal and ring condition. At just under 150K I run Lucas Oil Additive for this reason (1 quart Lucas and 4 quarts High-mileage formula conventional motor oil). Consider a product like Seafoam to clean out the crud. Many here have seen noticable difference in performance and mileage after a dose of this stuff in the crankcase. Take a moment to peek down the throttle bores as well. If they and/or the throttle butterflies are black with soot and gum, clean with throttle body cleaner. Make certain that the product you use is safe for throttle bodies and O2 sensors/catalytic converters.

 

I got almost 1 mile to the gallon better when I used synthetic motor oil. My father uses it in all of his vehicles and has had the same results. Also, have you thought about a less restrictive air filter?

 

I dont think a switch to a full synthetic oil at 200K+ miles would be wise at all. I like full synthetic oils and have used Mobil 1 in my turbo charged Volvo since the first oil/filter change after normal engine brake in, but its not a good idea to switch over on a high mileage engine though.

 

My son drives my 88 (5.0 auto) back and forth to school each day. He gets about 10 mpg also. The school is only 2 miles from my house. I think the mileage he gets is not too bad since it never warms up. I drive it occasionally and the best I get with it is 12 mpg. It has 208,000 miles on it so I don’t complain. I run platinum plugs in it because it seems to run better. I only run 87 octane fuel in it because I was told that it would run better on it.


What fuel does everyone else run?

 

Mid-grade...whatever the octane rating is on average for it. 10 mpg is not the greatest even for these behemoths. I consistantly get 12-14 in the city with the ocassional spike to 16-17 on long highway runs. I should mention though that I am currently pursuing the idea of adding an LPG injection system to help mileage, reduce emissions, and get the tax break for an alternate fuel vehicle. www.welshtec.com/page0011.html

 

I was getting around 8-9 mpg for a while and finally decided to chase down some of the engine codes that had been flashing. In the end, I replaced the O2 sensor, the air charge temp sensor and the coolant temp sensor.

Just got back from the gas station for the first fill-up after all those were replaced and the math came out to 12 mpg!! Not great, but a lot better. In hopes of getting it to work with the spout connector in place, I'm going after the EGR next.