followed by a lubricity-only additive (Opti-Lube's XPD), and finally, FPPF's 8+ Cetane Improver.
Did Solely Increasing Fuel Lubricity Increase Mileage?
To find out if the above question was true, we decided to run a two-stroke oil pre-mix as an additive in our test vehicle (unconventional at best, and with no cetane improvement). And after 2,000 miles of testing the product, the answer was yes. Our overall mileage increased 1 mpg in combined highway and city driving. Now, is it worth running this as an additive to gain a measly mile per gallon? You be the judge. But for less than $10, we got a 7 percent improvement in fuel economy and enough oil for 10 tanks worth of testing.
Opti-Lube XPD
At the time of our test, Opti-Lube's XPD formula was rumored to be one of the best diesel additives on the market. Along with providing lubricity-enhancing ingredients, XPD also claimed to increase each tank's cetane number by three to five points when mixed properly. In addition, Opti-Lube stated that its product contained injector cleaning agents, could improve not only fuel economy but water separation in fuel, and help cold weather performance as well.
FPPF 8+ Cetane Improver
Another highly regarded fuel additive is FPPF's 8+ Cetane Improver. And by running a 256:1 mixture, it claimed each tank's cetane number could be increased by 8 points. This meant that by filling up with 40 cetane or 45 cetane fuel at the pump we would still be able to make our fuel as energy-dense as possible. Along with increasing cetane rating, FPPF's additive was also capable of reducing smoke and engine noise, and providing quicker start-ups.
Conclusion
Please check out our results, which should dispel any rumors that all fuel additives are a gimmick, or a myth. At least in our '97 Power Stroke's case, the myth has been proved, rather than busted-the fuel additives we tested did increase fuel economy.
Test Vehicle
Year/Make/Model: 1997 Ford F-350 4x4 Crew Cab
Engine: 7.3L Power Stroke
Transmission: E4OD Automatic
Axle Ratio: 4.10
Tire Size: 285/75R16
Modifications: Upgraded fuel injectors from Full Force Diesel, TS Performance six-position chip with daily driver setting from Bean's Diesel Performance, free-flowing K&N air intake and MBRP 4-inch exhaust, and upgraded transmission from North American Diesel Performance
Test Variables
• Each additive was mixed at the manufacturers' recommended ratio and poured in the empty tank first, before filling up with fuel. (Opti-Lube XPD = 256:1, FPPF = 256:1,
the two-stroke, which had no recommendation, was run in a 200:1 mixture).
• The same three filling stations were used throughout testing, and the truck was topped off at the same level each time.
• Real-world driving scenarios: stop-and-go city traffic, interstate commuting (65 to 70 mph, cruise control), and minimal off-road use. Note: Hauling and towing instances were purposely excluded from the test results.
• Eleven thousand miles were driven during testing: first with no product, then with two-stroke oil, Opti-Lube, and FPPF.
• Weather did not play as big a role as one might think. With one of the mildest climates in the country, Southern California allowed us to conduct the test in a virtually uncorrupted manner (no freezing temperatures or extreme heat conditions were faced).
• Heat and air conditioning were rarely needed (no unnecessary drag was placed on the engine).
• Regular maintenance was performed on the truck. And because we were dealing with HEUI, we made sure our oil was changed every 4,000 miles for the cleanest oil possible actuating our injectors (we ran Shell's Rotella T Heavy-Duty 15W-40 engine oil). We also inspected and then replaced the fuel filter before switching to the next additive (no fueling or performance modifications were made to the truck once the testing began).
NO ADDITIVE
Highway Average
14.6 mpg
City Average
13.7 mpg
Overall Average
14.1 mpg
TWO-STROKE PRE-MIX
Best Highway (one tank)
16.3 mpg
Best City (one tank)
14.9 mpg
Highway Average
15.6 mpg
City Average
14.6 mpg
OPTI-LUBE XPD
Best Highway (one tank)
17.4 mpg
Best City (one tank)
15.7 mpg
Highway Average
16.1 mpg
City Average
14.4 mpg
FPPF 8+ CETANE IMPROVER
Best Highway (one tank)
17.3 mpg
Best City (one tank)
15.0 mpg
Highway Average
16.1 mpg
City Average
14.9 mpg
Cheers,
and
do some more research into additives in diesel fuel. There is always new information out there. This is relevant information but then
anyone can put the blinkers on and ignore it if they want to.
Jason