do any UCL's actually help gas mileage?

[Jasper8146]

On our 2003 Acura MDX, using Lucas UCL and fuel injector cleaner made a significant difference for the better regarding gas mileage. I'm talking about 2-4 mpg difference for the better. Quite noticeable. Also, Gumout Large Vehicle fuel injector cleaner made a significant difference in that Acura along the same lines--2 to 4 mpg better. Since we got rid of that car, neither of those products or any other product has made any difference in a 2011 VW Tiguan or a 2011 Infiniti EX. I am quite puzzled by the difference. What are other people's experiences? I can't fathom why the Lucas and Gumout would make such a huge difference in a 2003 Acura MDX but seemingly no difference whatsoever in a 2011 VW Tiguan and 2011 Infiniti EX35.

 

[Clevy]

Lucas contain polyisobutylene so it can affect fuel consumption.
As far as an upper cylinder lube I can't say for sure that mileage is increased every tank however for what it costs to treat my fuel I'll use it just to give me the warm fuzzies.

 

[yvon_la]

Side note:at the point car are these days,you need all kind of sensor in the engine bay to notice gain or lost

 

[147_Grain]

The increase in MPG's was likely due to dirty fuel injectors or the combustion chamber being cleaned up. Perhaps the Acura's injectors or valves were dirtier (and responded better) than the VW or Infiniti's.

 

[grantsburg]

Originally Posted By: Jasper8146
I can't fathom why the Lucas and Gumout would make such a huge difference in a 2003 Acura MDX but seemingly no difference whatsoever in a 2011 VW Tiguan and 2011 Infiniti EX35.


The older car had dirty fuel injectors. The 2 newer ones didn't.

But stick with top tier gas and I doubt your fuel injectors would ever get dirty enough to require a fuel injector cleaner.

 

[Boomer]

There have been some papers published that purport to show that the presence of a polymer in fuel can lead to a more efficient burning of the fuel, hence slightly higher mileage. Since Lucas is polyisobutylene (noted above inClevy's post), ths may be a part of your observation. I used this in my 2003 Saturn and saw some small mpg gains but saw NO effect at all with Lucas in my Frontier, so I kind of mirror your observations.

However, with small gains, you really can be seeing just statistical noise. I think for any of us to say that there is a real effect, would take many months of driving with and without the additive under reasonably controlled conditions. And that can be essentially impossible to do with a family car.

 

[dave5358]

Originally Posted By: Jasper8146
On our 2003 Acura MDX, using Lucas UCL and fuel injector cleaner made a significant difference for the better regarding gas mileage. I'm talking about 2-4 mpg difference for the better. Quite noticeable. Also, Gumout Large Vehicle fuel injector cleaner made a significant difference in that Acura along the same lines--2 to 4 mpg better. Since we got rid of that car, neither of those products or any other product has made any difference in a 2011 VW Tiguan or a 2011 Infiniti EX. I am quite puzzled by the difference. What are other people's experiences?

I have no experience with Lucas UCL and I generally avoid Lucas products. The only Gumout products I use are spray cans for cleaning carb parts, throttle bodies and the like. Also, the composition of UCLs varies a lot - from 'mostly solvent' to TWC3, which is mostly oil.

My experience with MMO (solvent and light oil) has been favorable. It stopped valve burning and increased MPG. The increase in MPG was slight but quite real, as supported by increased cylinder pressures (and therefore not subject to the myriad driving variables that cloud MPG results). The full test and circumstances are described here - about mid-way down this page - message #3204737.

The gist of test was this: the MMO was put into the engine by an oiler, so it was easy to stop or start the UCL flow. When the UCL was flowing, the cylinders were measuring ~5 psi more pressure. Stop the UCL flow and the cylinder pressures dropped. This test should be easily repeatable (but not on a Subaru ;-) as long as 1) you have a method of stopping and starting the UCL flow and 2) the spark plugs are readily accessible, since you will be pulling and re-installing the plugs while the engine is hot. Driving around the block was adequate to clear out the engine of residual UCL.

Note that it doesn't matter if the cylinder pressure increase was 5 psi or 1 psi, as long as it was a genuine increase. But unlike measuring MPG, measuring cylinder pressures is pretty straight forward. Remove the plug - stick in the gauge - spin the engine - a check valve holds the highest reading. Even a valid 1 psi increase on average will mean better fuel efficiency or more power. A quality compression gauges should be able to measure to the nearest pound, with good repeatability.

 

[Kuato]

2003 vs 2011. If you repeat the treatment on your 2011s in2020, you may see a difference.