funcrusher

Do any of these really work? I've read of people getting better MPG and a smoother drive and also stories of people getting worse MPG! Fill me in....

Oro

I like SeaFoam.

I used it a long time on motorcycles to keep carbs clean; worked great. A rough running bike would smooth out in one tank ( 1 oz. per gallon). Basically like magic since it prevented you having to tear down and clean carbs and synch them - a laborious and difficult task.

I started using it on cars a few years ago. Most dramatically, I cold soaked my cylindres on an Acura SLX with it. They have a known problem of clogged/coking oil control rings. I went from burning 1qt of oil per 1k miles (sometimes more) down to basically none.

It works as advertised. I have also used their "Transtune" to clean up transmission and PS systems - added it for a while prior to changing fluid. Made a difference. So yes, there are good products out there that can help your car if it has a problem: varnishes/coked rings/dirty injectors/etc. I know that at BITOG (that is where they treat oil and additives like fine wines), there are adherents to this, MMO (marvel mystery), and Auto-RX among others. Many things do work depending upon the exact nature of your problem and what you want to achieve.

funcrusher

My car is shifting a little rough and it's getting on my nerves. It also sometimes doesn't start up instantly and butter smooth like my old Lexus

Oro

I would do a few things:

1) add some transtune, drive it. Then drain and fill the tranny. If it is really nasty looking, you can disconnect the cooler line, pump some out (by running car), refill, repeat. Got to be careful with that process so as not to run it dry or suck air in. Not too hard.

I have had this clear up hard/variable shifting on higher mileage cars. Sometimes it is varnished contacts/solenoids, etc., low fluid, bad fluid, etc.

2) Many reasons for rough running. Google "clean isv" or throttle body and you will get good, clear instructions from DIY threads here. Also check/replace ISV valve, check plugs, etc.

PFB

Be very cautious when using any fuel injector cleaner.

A) Unless it says catalytic converter friendly somewhere on the label, don't use it.

B) Even when it's labeled as catalytic converter friendly, be aware that if not used as per instructions, or used too often, it can permanently damage your catalytic converter.


Phil