Fuel Economy Tips - Fuel Savings: Fact Or Myth?

The good folks at Off Road Unlimited in Burbank, California, performed the installation of the Free-Spin kit for us. The whole process is rather simple; remove each front wheel, axle, and hub assembly and replace the outer parts with the Dynatrac pieces. The Free-Spin conversion is available for solid-axle Dodge Ram and Ford Super Duty pickup trucks. We got our Free-Spin Kit from KLM Performance of Wilton, Connecticut. With the Free-Spin conversion installed, we first noticed a generous improvement in steering feel. What once caused motion restricting steering feedback was now absent. Negotiating maneuvers in tight parking lots was much easier. In our subsequent testing, we noticed a 1.86 mpg gain on the highway. However slight the increase, the Free-Spin conversion is a worthwhile investment because it eliminates those expensive unit bearings and replaces them with traditional-style tapered roller bearings. This setup saves you money when the time comes to replace front-end bearings.

Next we continued in our quest to reduce friction and had both the front and rear differentials serviced. Upon doing so, we had the guys from Off Road Unlimited swap in a set of Mag-Hytec differential covers. Our logic was simple; reduce operating temperature inside each differential and prolong diff lube life. Aside from looking cool, the Mag-Hytec diff covers feature O-ring seals, finned cooling, a magnetic drain plug and temperature probe ports.

Another product that we tested that claimed to improve fuel economy was the Fitch Fuel Catalyst from Advanced Power Systems International. In the simplest of terms, the Fitch Fuel Catalyst modifies fuel prior to the combustion process, neutralizing it of undesirable effects of storage and transportation. In a nutshell, fuel is attacked by oxygen, ozone, and microorganisms (bacteria, yeast, and mold) that grow in storage tanks and delivery pipelines. A less-than-optimal fuel will produce less engine efficiency, less performance, more emissions, soot buildup, and deposits in engine oil and injectors. By installing a Fitch system, the fuel is treated with the catalyst material on board the vehicle, re-refining the fuel to its most optimal state allowing the engine to produce maximum performance and efficiency.

When we did the differential service, we used genuine Royal Purple gear lube. Royal Purple gear oil is a synthetic lubricant designed to decrease friction and extend bearing and gear life by creating an ionic bond between the oil and metal for continuous protection. While we didn't see any additional increase in mileage afterward, we did notice that the differentials ran cooler with the improved lubricant. We used a laser temperature gun to prove this. In every scenario the Royal Purple oil was 55 to 108 degrees cooler running than the factory lube with more than 44,000 miles on it.

The next product we tested was an electric fan conversion by Flex-a-lite. Designed specifically to replace the stock beltdriven fan, the Flex-a-lite unit features dual 15-inch 12-volt motors that spin eight composite S-blades up to 2,100 rpm. The effect of this product is reduced drag on the engines accessory drive system. The claimed fuel savings results from this reduction in engine drag. We weighed the OE clutch fan assembly once it was removed from the truck and were surprised to find it weighed 13.4 pounds. By removing the beltdriven unit, the engine does not have to spin the mass of the fan and clutch assembly, nor does it have to overcome the drag associated with airflow spinning the fan as the vehicle moves. Our testing didn't result in the claimed 6 percent fuel savings, but the unit did net an additional 1.12 mpg over the data collected prior to its installation. The unit we tested was pretty easy to install, the hardest part being removal of the factory clutch-fan assembly. Once installed, the polished-aluminum shroud assembly added a trick racer-appearance to an otherwise plain-looking engine compartment. We must note that Flex-a-lite doesn't recommend this product for those who tow loads in excess of 18,000 pounds regularly.

If we had to categorize the products we tested on a scale of 1 to 10, 10 being the product with the most significant impact on mpg, we would have to give the next product a 10. Say hello to the Gear Vendors overdrive unit. This secondary transmission enables drivers to drop into a double overdrive gear while cruising at highway speeds. The effect lowers engine rpm significantly, allowing less fuel to be consumed. We were amazed at how quickly we noticed an outstanding savings of 3.22 mpg when the unit was in use. The unit features an automatic and manual mode and is equipped with a foot-operated engagement switch. The device installs in place of the transmission's tailhousing. Only the rear drive axle can benefit from the overdrive once it's engaged, therefore an electronic interlock control unit comes with the product to ensure proper operation. If wired correctly, the Gear Vendor unit will not work in four-wheel drive. We thought we should mention the additional maintenance required by the device as the unit features its own lubrication system. In heavy towing applications, Gear Vendors suggests changing the unit's oil every 5,000 miles, though we let ours go to 10,000 miles and found it functioned properly.

The Fitch unit installs inline, much like a fuel filter. As you can see here, we simply zip-tied it to the framerail under the driver side of the truck. While our testing didn't net the claimed maximum gain of 2.5 mpg, it did see notable gains to the tune of 1.37 mpg over 4,383 miles.

End Results
Our best fuel economy was observed while driving in double overdrive with the truck unloaded, the hubs unlocked, the Fitch and electric fans hooked up, and while traveling 55 to 60 mph on flat asphalt roads. The average for this scenario was 21.13 mpg, not bad for a 3/4-ton pickup on 34-inch-tall tires. While towing, our average increased to nearly 15.5 mpg over a 2,408 mile trip.