Has anyone who uses additives experienced a loss in MPGs?

[OlyTDI]

I'm in the process of trying to figure-out why I've suddenly taken a 5 - 6 mpg hit. There are two variables that I can tie to the time when this started in May of this year: I lifted my car with a complete suspension refresh, and I started using Opti-Lube XL Extreme (only for lubricity).

I posted a poll asking if anyone else who's lifted their car has had such a hit in MPGs. No one who responded had. I've not similarly posted about the Opti-Lube but I cannot imagine that 1.5 oz in 14 gallons would do that.

Anyone have any input with additives and MPG gains or losses?

I'm trying to be systematic with analyzing this. Car otherwise runs like a champ. No problems or codes.

Thanks up front!

 

[CrispTDI]

well you could stop using the opti-lube for a couple of tanks and see if that changes anything...

Otherwise my bet would be lifting changed aerodynamics. Have you changed your driving habits at all? even doing more stop and go driving, or driving faster on the highway?

edit: one other thing I thought of. Have you been using your A/C more? That could be a factor.. assuming you get 45mpg you are looking at about a 12% drop in efficiency which is not that dramatic. So lift plus A/C usage could cause that, also check tire pressure just in case.

 

[murphyslaw]

I have used Opti lube XL, XD, Winter and Summer Plus. never saw a drop in mileage, most the the time there was simply not a change at all. I have also used Various Power Service products, as well as Amsoil diesel treatment. None have ever hurt mileage. The only thing that seems to hurt the MPG in my car is to let my wife drive it.

In the winter my MPG average 44.6 in the summer they average 45. I figure the better fuel in summer is offset by the 85% utilization of AC. And I dont idle for warm ups in the winter either.

 

[Powder Hound]

My first thought was maybe wider tires, but since you didn't mention that, I assume no changes in tires were made. But, besides tire pressures, perhaps the lift changed the geometry which changed the tire patch enough to affect the mileage. It is something you'd need to check at an alignment shop.

Cheers,

PH

 

[ZippyNH]

You lifted your car up.... aerodynamics. Pure and simple. 12% reduction in economy....higher ride.
That's my bet.
A couple inches CAN MAKE. A huge difference....air getting under the car...adds drag.

 

[pparks1]

I experienced no change with additives, positive or negative.

 

[OlyTDI]

Thanks much, everyone, for the replies.

My driving route and habits haven't changed.

I use the AC the same pretty much year round. No changes there.

I would have guessed aerodynamics but everyone else who chimed in with my questions to those who had lifted stated that they had no change whatsoever. Not one person stated that they took a hit.

Tires are newish (have about 6K or so on Pirelli P7s) and the alignment was done during the refresh and I saw the spec sheet. Tire/wheel size did not change.

Dropping the Optilube for a couple of tanks with comparison is a good idea -- thanks.

Open to other conjecture!

Thanks guys!

 

[Rico567]

We have used Opti Lube since new on our car, so unfortunately I can give no basis for comparison running without it. Our FE figure for about 45K miles (always done with pencil & paper) can be seen in our Fuelly sig. No modifications have been made to the car since new, still running OEM Conti Pro Contact tires.

 

[bmwM5power]

ive used luqui moly super diesel additive and got mpg increase on both mk4 and mk6 tdi, ive found this is the only one additive that really works

 

[OlyTDI]

Only additive that really works for what?

 

[bmwM5power]

Only additive that really works for what?

for what it says on the bottle

 

[Lightflyer1]

"Cleans the fuel system and improves combustion"

"Liqui Moly Super Diesel Additive for a cleaner engine and better performance."


https://www.europaparts.com/liqui-m...b***tcvPPlelZF5lALj-GMAU62WW1BA8BwaAp-h8P8HAQ

BENEFITS:

Cleans the injection system and protects from contamination and corrosion
Improves the lubrication action of diesel fuel
Protects injection pump from wear
With Cetan Booster for greater engine performance, less Diesel knocking, quieter running and easier starting
Prevents corrosion and contamination in fuel tank, pipes and injection system
Complies with the federal low sulphur content requirements for use in diesel motor vehicles and nonroad engines."

Mostly stuff you wouldn't be able to tell without doing a tear down and microscopic examination. Nothing a normal person could tell by using it other than quieter maybe. Says nothing about an increase in fuel economy.

 

[OlyTDI]

Okay, I get it. Thanks!

 

[bmwM5power]

Says nothing about an increase in fuel economy.

" With Cetan Booster for greater engine performance" this will make an increase in fuel economy, at least it did for me

 

[Lightflyer1]

But it doesn't say that on the bottle, like you said. Greater engine performance can be many things.

 

[bmwM5power]

But it doesn't say that on the bottle, like you said. Greater engine performance can be many things.

look, im not sure what youre trying to prove here, this is very simple stuff , if it doesnt work for you or you have some other reason why not to use it, then just dont use it. maybe optilube, stanadyne, or nothing works better. i was just responding to the op and shared something from my own experience with the fuel additives

 

[tdiatlast]

^^^Thanks for posting your experience. That's what the OP asked for.
However, it isn't, "...very simple stuff...". Isolating the CAUSE of an MPG increase/decrease is in fact impossible w/o strict controls. There are just too many variables.
Your experience is valid. However, it can't possibly be used as "proof" that others would achieve the same results.

 

[showdown 42]

Most people who use some sort of roof box will experience some degree of mileage loss,which I did,so My guess is the "lift " is causing the decline in mileage. Wind Resistance is the culprit.

 

[OlyTDI]

Thanks Showdown. I suspect so as well but in the admittedly poorly responded-to poll I posted asking if others who had lifted also had experienced a MPG downgrade, the results were mostly in the "no difference" camp.

Anyway, it's a mystery that may remain so. It's just a little disappointing in that I really liked getting my 700 miles per tankful!

 

[alma]

look, im not sure what youre trying to prove here, this is very simple stuff , if it doesnt work for you or you have some other reason why not to use it, then just dont use it. maybe optilube, stanadyne, or nothing works better. i was just responding to the op and shared something from my own experience with the fuel additives

I, too, experienced an increase in power and higher mpg when using Liqui Moly's Super Diesel Additive. I have tried 4 other additives, but none seemed to work better than this one.