Originally Posted By: NattyBoh
So my wife's car is about to hit 100k. I have used Amsoil PI at I think 70k. I have MMO here in gallons, but don't know which what I should go. Aggressive with a PEA or use a slow cleaner like MMO...
Since you are not having problems, it's unclear what you want to fix. But, at 100K miles, the wife's car is no longer new. You might check compression in all the cylinders - dry, wet, leak-down. That will give you a better picture of the engine's condition. Engine problems tend to creep up unnoticed.
You might also go through the engine replacing vacuum hoses. At 100k, the rubber hoses are hardened from engine heat. Since most vacuum hoses are non-reinforced, when they become hard or brittle they may still form a seal, but they don't seal as well. Leaky vacuum lines might result in a big fail, but more likely just an accumulation of small leaks. You did not indicate if you kept mileage records. If so, you might discover that the vehicle is not as efficient as when new - due, at least in part, to minute vacuum leaks.
If you are using
Top Tier gasoline - even using it occasionally, perhaps without even knowing it - then you are getting a dose of PEA or equivalent fuel system additives with each tank full of gas. It's unclear why you you would need to add more. But a can of PEA-based additive through the gas may not hurt anything (but see the comment below regarding 'aggressive' fix).
MMO added to the fuel is a bit more than a cleaner. Before you take advice or criticism of MMO from the BITOG trolls who dislike MMO for unspecified reasons, you might ask if they have ever used it and to describe their specific experiences with the product. As for Gumout/Regane, you might check the
Gumout website (or maybe this forum) to determine which products contain what ingredient. When Gumout acquired Regane several years ago, there seemed to be a bit of confusion regarding the continued use of the Regane name.
Redline also makes a popular PEA-based fuel system cleaner. MMO does not contain PEA.
Sea Foam is another popular fuel cleaner which does not contain PEA.
Two final thoughts: If you have been using decent gasoline of the correct octane rating for your engine, it's unclear why you need to 'clean' your fuel system (aside from any cleaning done by additives already in the fuel). If you go "aggressive" (your words), the crud that gets cleaned has to go somewhere. There are numerous threads in which users describe darkened oil after the use of PEA-based cleaners, and one unhappy
BMW owner who claims the crud all went to his injectors (and stopped there!).