Piston Slap: Fuelish Thought on Additives?

Sajeev Mehta
by Sajeev Mehta
piston slap fuelish thought on additives


Robin writes:


Longtime reader, first time writer. I love reading your stuff, well worthwhile.

My query is about fuel additives, after-market specifically. I have used the Lucas Oil products and found them to produce a mile or two better MPG in my 94 D21 four banger. (Note: that’s a Nissan Hardbody – SM)

What is your take on additives? Have you found any others to be of significant value to the user/user’s vehicle?

Sajeev answers:

Great question, with a pretty short answer: additives are usually useless in cars that are well maintained. That’s in general. Some people swear by Lucas additives, but I am not sure of their benefit over consistent usage of synthetic fluids over the course of a vehicle’s life. And that’s worth keeping in mind, no matter how “special” you feel your circumstances may be. Can the magic bottles really be that special in something as honest and durable as a 1990s Nissan truck? Your case seems pretty clear cut.

Then again, fuel system additives are one exception, they sometimes do a great job at removing gunk (especially with varnish/corrosion/deposits that supposedly occur with E10 gas) in the fuel system, the tiny screens in the fuel injectors in particular. I haven’t personally experienced a benefit from fuel injector cleaner, but I do occasionally use it as preventative maintenance on my old cars in the land of E10 at the gas pumps. But a mile or two better MPGs? That’s pretty impressive.

That said, make sure to change your fuel filter as per manufacturer recommendations. Or sooner. That’s often a bigger problem for your fuel system.

Bonus! A Piston Slap Nugget of Wisdom:

My only additive of recommendation is Seafoam. Seafoam seems to fix everything…in motors with a lot of miles and a lot of carbon buildup. Sure, it makes a colossal mess while de-carboning the upper half of a motor, but it often improves throttle response, fuel economy and sometimes even emissions. After it increases your carbon footprint exponentially, ‘natch. This stuff is also supposedly a good fuel system cleaner, oil gunk remover and probably helps men with their Viagra-related concerns. (kidding!)

Not that I recommend everyone spend the $8 or so to try it out on your motor, but if you start running out of options after a proper tune-up on your old hooptie fails to give you satisfaction…give it a shot.

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry.

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2 of 42 comments
  • Ian Anderson Ian Anderson on Aug 30, 2011

    Only additives we use in my house are Seafoam, Lucas for the oil and Stabil for the winter (and in the generator etc). The Seafoam's good for pissing off the neighbors, especially if said neighbors piss you off with car-related stuff. That and it does seem to work, made the S10's 4.3 idle smooth (well, as smooth as a 90º non-balancer V6 can be) and under the valve covers looked better. My Dakota's 3.9 is next! The Lucas we use in the Metro since it has leaky valve seals and puffs oil smoke at start up. It seems to have cut down on that a lot, either me or my dad will add 1/2 a quart to the oil every change. Before I started driving it the S10 got some benefit from it too- the 4.3 suffers all the same high mileage valve-seal problems as its small block parents. Now I just ignore it and check the oil! As for the Stabil it's good for keeping gas from turning into varnish, or at least our generator, lawn mowers, weed whacker, hedge trimmers, etc make it seem that way.

  • Rrhyne56 Rrhyne56 on Aug 31, 2011

    been out of town and return to find this piece on my favorite site! My cousin had some thoughtful input that made me feel a bit better about using Lucas: " I use Lucas in all my cars. Not for fuel economy but to keep rubber parts lubricated (especially on the 30 year old bimmer). Ethanol is horrible for that stuff. It also helps to lubricate the fuel pump and its associated parts and the upper cylinder walls as well as helping to prevent carbon buildup."

  • Robert I have had 4th gen 1996 model for many years and enjoy driving as much now as when I first purchased it - has 190 hp variant with just the right amount of power for most all driving situations!
  • ToolGuy Meanwhile in Germany...
  • Donald More stuff to break god I love having a nanny in my truck... find a good tuner and you can remove most of the stupid stuff they add like this and auto park when the doors open stupid stuff like that
  • John Williams Sounds like a Burnout Special you can put together on any 5.0 F150. Whoever said this was Cars and Coffee bait is right on the money.
  • ToolGuy Question: F-150 FP700 (  Bronze or  Black) supercharger kit is legal in 50 states, while the  Mustang supercharger kit is banned in California -- why??