Do you use a fuel additive? (And if so, which one?)

nderwater said:

Both of my cars have direct injection so i feel that additives are pretty important to use--but I don't have any objective way to know whether these additives area really needed, or if they're even making any improvement to the health or performance my engines.

This is something that I have recently been wondering about as both of my cars are DI (my MX-5 and my wife's CX-5.  Part of the reason that additives were put in the gasoline was to clean the valves and intake track, but since the DI system puts the fuel directly in the combustion chamber, is there really a benefit?

Top tier gas and MMO once in a while.

My Techron data point is now exactly 30 years old- back when I worked at Chevron as a intern, we did a lot of testing of Techron and Techaraline- which were pretty awesome.  The only thing better at the time was an additive that Exxon Mobile had, which was actually sold to them by Chevron.  That's when I really learned a lot about intake system deposits, and my first exposure to how bad BMW's happen to be (and they've never gotten better, for some reason).

But I also know that the detergent packages for base gas changed when the emissions standards tightened quite a while ago.  Mostly making the extra detergents not needed.  Unless you had a specific problem to address.

miatafan said:

nderwater said:

Both of my cars have direct injection so i feel that additives are pretty important to use--but I don't have any objective way to know whether these additives area really needed, or if they're even making any improvement to the health or performance my engines.

This is something that I have recently been wondering about as both of my cars are DI (my MX-5 and my wife's CX-5.  Part of the reason that additives were put in the gasoline was to clean the valves and intake track, but since the DI system puts the fuel directly in the combustion chamber, is there really a benefit?

Yes, as there are still combustion chamber deposits as well as injector deposits.  Plus not all DI engines have intake deposits.

I have Seafoamed some of my engines, but I don't have a definite opinion, which is why I asked for clarification on the recent thread. 

I did also explain that Shell premium was the only fuel that ran normally in my boosted but non-tuned Tacoma. 

In June of every year I buy multiple cans of ethanol-free gas with Stabil added, this sits in storage until the end of hurricane season. If I haven't needed the generator by the onset of winter, I run it in the cars over the next few months. 

Thanks for starting this discussion. 

Top tier fuel makes most DIY additives completely unnecessary.  

I get using a bottle of techron or similar on an old/unknown car purchase with questionable prior owners, but thats just catching you back up faster.  No benefit if you use the correct gasoline from the beginning.  

I use marine stabil in the carb'd bikes, boats, and lawn equipment that sit over the winter due to ethanol concerns.  

is there a list of contents that have to be sent to the EPA ?

Since  most want to say "trade secret" is there anyway to really know what they contain ?

bentwrench said:

CRC intake valve cleaner really works I am surprised the EPA has not pulled it from the shelves!

DI motors don't get fuel sprayed at the intake valves and the PCV gack builds up on the back of the valves.

CRC works! It is like the old combustion chamber cleaner sold by Ford in the 80's.

I soaked pistons from a motor with a carbon knock with 4 different products and CRC won hands down the pistons look like new.

Just ordered a can, will report back. Wife's 2012 Accent is GDI and the idle is rougher than I'd like for a car with only 100k on it. 

I use BG 44k in the tank. 

I happened to look at a can of Seafoam and noticed that it was mostly alcohol, and that it was developed long before gasoline had ethanol added to it as part of the most common formulations. Alcohol is hygroscopic, so I can see that back in the day adding it to some of "last month's gas" might possibly help move a bit of water trapped in the system OUT of the system, but modern gasoline is doing that already with the alcohol in it. 

I think this is also why ethanol blended gas might get "old" before non-ethanol blended gasoline does.

As others have noted, I think modern Top Tier gasoline with 10% ethanol is doing all of the cleaning that needs to be done in the primary fuel path. 

Seafoam may still have a benefit through the intake path, I'm interested to see what the experts say about that.

I do seafoam/bg/crc treatments on the intake path.

As far as tank additives I only use techron on cars that commonly have fuel level sender problems like C5 vettes. I have personally seen it restore a non reporting fuel sender on a Pacifica after two tanks. Some googling said deposits on the sensor can stop them from working so we dropped some techron in, in two back to back tanks and boom it started working. So then my C5 got it about every 6 months,and my old ass truck gets it like once a year.

MadScientistMatt said:

I've used Sta-Bil on the lawnmower before it gets put away for winter. Trying to avoid another carburetor replacement on that one.

Then there was the time we took a Miata from DIYAutoTune to PRI, back when it was in Florida, and we were using it for the demo car on the Dynapak dyno, which was outside that year and we got to do live dyno pulls. The car had been tuned for 93 octane, and we could only find 91 octane. To boost the octane, we went to a Sherwin-Williams, bought a couple gallon cans of toluene, and dumped it in the tank.

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I had what I assume was an issue with a sticky injector in the Buick and now I regularly run BG 44 or CRC through it. It seemed to have helped and at 185k it runs almost as smooth as new.

I run premium Shell in the 'V' (2010,M6 @ 159Kmi) and every so often(once a month) I'll throw a can of SeaFoam down the pipe. and will usually see an improvement (1-1.5mpg) on the next tank...I'm not a stop light bandit (wink)  and have been making some 75 mile one way trips lately and have seen upwards of high 20's to low 21's at steady state 68-73 mph on the toll road/local freeways....

I've used HEET and/or Lucas if I had watery gas.

I used to use Stanadyne Performance Formula on every fill-up on our first CR TDI for most of it's life, 5 years 101K miles.  On our 2nd TDI I mostly only used it during the winter.  Now we're on our 3rd TDI and I don't put anything in the tank.  I'll fill the fuel filter canister up with Liqui Moly Diesel Purge when I change the fuel filter, but that's it.

Otherwise, I've frequently been known to use Seafoam or Marvel Mystery Oil, in the tank and crank case, a few hundred miles before an oil change.

I've had better luck with MMO making old gas useable, than anything else I've used.

When I was a service writer we pushed BG and Valvoline products, I've used their snake oils too, though 44K seems to be fairly legit.

I keep a 5 gallon Jerrycan on hand for lawn equipment and occasional offroading, it's always got Gulf ethanol free 87, and the appropriate amount of Stabil in it.

In reply to jharry3 :

In the 80’s F1 turbos were running 80% toluene because it was denser than pump gas, packed more energy, and had a high detonation threshold. 

bigdaddylee82 said:

When I was a service writer we pushed BG and Valvoline products, I've used their snake oils too, though 44K seems to be fairly legit.

I'm performing a BG oil restoration as I post this, so I'm getting a kick, etc.  (FARK.com meme)

The air induction decarbonizing works at least as well as the Run-Rite process I used to do, although it takes f-o-r-e-v-e-r to do.  I did two of them yesterday at 35min each.  Fortunately the wi fi reaches outside 

The power steering flush is magic, BTW.  Wouldn't have believed it until I did one.

What about the ps flush was so good

I've used Lucas a lot in smaller engines , makes chainsaws run great

It also helps my ranger with lifter tap a bit, although I need to stop being lazy and fix that

Opti said:

What about the ps flush was so good

It solved two whiny Ford power steering pumps for me.

In reply to Knurled. :

I don't think it will work on my FiST though.

jharry3 said:

Does toluene really work for an octane booster?  Or as a BTU booster?   I find mixed information for that on the internet.

It absolutely works, but you need to tune for it. In the Turbo F1 era, teams were running fuel mixes with more toluene than gasoline.

I'll use Techron once or maybe twice a year, and in the fall put some gas stabilizer in cars that get stored over the winter - usually Sta-Bil, but sometimes Seafoam; it depends on whether one or the other is on sale.

I don't know if additives make any difference, but I've been using them with my carburetted engines after people scared me about ethanol. I've used Lucas "Upper Cylinder Lube" in the past. Lately, I've switched to Marvel Mystery Oil (MMO).

Again, I  have no idea whether it actually does anything useful.

californiamilleghia said:

is there a list of contents that have to be sent to the EPA ?

Since  most want to say "trade secret" is there anyway to really know what they contain ?

You can look up the MSDS sheet for most commercially available chemical products to find out what they contain.  For instance, here's the one for Marvel Mystery Oil: http://www.marvelmysteryoil.com/media/1256/marvel-mystery-oil.pdf  Note that there are a lot of websites that want you to sign up to view MSDS sheets, but more often not you can simply Google on "[product name] MSDS" and find them.