Piston Slap: Fuelish Thought on Additives?

Sajeev Mehta
by Sajeev Mehta


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.

Sajeev Mehta
Sajeev Mehta

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  • 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."

  • Lou_BC Question of the day: Anyone actually care to own an old TVR?
  • Bd2 First, this was totally predictable. 2nd, Genesis already does have hybrids in the form of a 48V mild hybrid, but more performance oriented (supercharged and turbocharged), so not really helping with regard to fuel consumption. 3rd, Hyundai's hybrid systems don't really help as there currently isn't one that would be suitable power-wise and the upcoming 2.5T hybrid system would have to be heavily reworked to accommodate a RWD/longitudinal layout. 4th, it seems that Genesis is opting to go the EREV route with the GV70 the first get the new powertrain.
  • Bd2 Jaguar's problem was chasing the Germans into the mid size and then entry-level/compact segments for volume, and cheapening their interiors while at it.
  • 3-On-The-Tree Aja8888 I expected that issue with my F150 starting at 52,000mi. luckily I had an extended warranty and it saved me almost $8,000. No more Fords for me, only Toyota.
  • Lou_BC I saw a news article on this got a different read on it. Ford wants to increase production of HD trucks AND develop hybrid and EV variants of the SuperDuty. They aren't scaling back EV production. Just building more HD's and EV variants of HD's .