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

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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.

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