Q: Bad gas mileage and always runs in 4WD - 1979 Chevrolet K20 350 V8

asked by on

My truck is all the time running in 4WD and the gas mileage is terrible. I have changed the oil, transmission fluid, filter, and installed duals with turbo mufflers. After all of that, my truck still only averages around 10 mpg. When I first start driving, it is a bit sluggish. I am thinking that I might get manual lock out hubs for the front to take it out of 4WD. Perhaps I will invest in a top-rate filter system like edelbrock. What is your advice for how I can get my truck to perform with better gas mileage?

Hi there, thanks for your question. Yes, these older Chevys do have full time four-wheel drive. There are kits available that will disengage the differential from the transfer case, but I’ve heard mixed reviews on how well they work. You could also convert your full-time NP203 transfer case over to a 205. If you’re doing this solely for mileage, however, I would think twice. Really, 10 miles per gallon isn’t bad for your truck. Converting to part time four-wheel drive might net you a little better mileage, but the time, effort, and cost will probably outweigh the mileage gain. If you think your car should be getting more mileage than it is, consider having one of our certified automotive technicians come to your home or office to diagnose and repair the issue for you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Bad gas mileage and always runs in 4WD - 1979 Chevrolet K20 350 V8

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: After multiple replacements, gas mileage is worse - 1997 Ford Aspire

The fuel economy will change depending on the whether the transmission is manual or automatic. According to fueleconomy.gov the manual transmission Ford Aspire is getting a combined 33mpg while the automatic get 26mpg. Ford's initial adverts were 34 mpg city...

Q: Is lucas oil stabilizer ok to use in a 99 bmw 323i, if not what makes it bad to use?

Hello. BMW doesn't recommend using oil additives. I don't know exactly whether Lucas Oil Stabilizer works well, but if you are using a good quality oil with an SJ rating or better, there is not anything that an additive is...

Q: Fuel economy getting worse on a 2000 Opel Astra G

You generally get bad fuel mileage for either the air filter that is clogged or the MAF sensor that measures how much fuel goes in to see if either is dirty or needs to be replaced. Fuel injectors could be...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.