Originally Posted By: SLCraig
Originally Posted By: gathermewool
I tried it for a while and couldn't discern a difference. I'm currently trying SI-1, but haven't noticed any difference with it either. It's harder to tell with my current car since gas mileage changes every time I change maps or decide I do or don't want to boost stay in boost often.
I'm not sure how you're able to discern 0.5 mpg, though. That has to be within the +/- of simply fuelling up at different pumps, let alone changes in tank-to-tank driving habits.
-Hata fo life
Well SI-1 is a fuel system cleaner so there is a good chance its doing nothing because there is nothing to do. I can't speak for MMO, but I have used SI-1 and I've had it restore some power on old tired engines before.
From what I've read, it's only half cleaner, with 30-50% PEA, and has some UCL properties. I'm currently using it at 5 oz./fillup, but may lower it down to 3oz. fillup soon.
You're right, though, and my main reason for running the maintenance dose is to keep things clean, though it is most likely not necessary while running nothing but Mobil and Shell fuels.
Originally Posted By: TedSexington
I agree expecially on a 08 STI. If your using quality gas and is on a newer car no need for fuel system cleaner (unless for extra insurance), but for older cars it may help. Also some cars will take it differently than others.
I forgot to mention in my last post that I ran a couple of bottles of MMO (can't recall whether they were pints or quart bottles) through my old '97 Subaru Legacy with around 175k miles and tracked mileage and performance with my scangauge, as well as hand calcs. I actually started using it in hopes of quieting a noisy fuel pump. I did not notice any change in consumption nor performance, and replacing the fuel pump cured the noise.
Just my experience. I'm obviously willing to try "tried-and-true" additives (in my gas tank,) but that doesn't mean I believe they do anything more than produce a tickle on the butt dyno.