Red Line60103 SI-1 Complete Fuel System Cleaner - 15 Ounce (12 Pack)

Redline SI-1 is currently the best fuel system cleaner that is readily available. One of the best examples supporting this statement is represented by the condition of my 2003 S2000's engine. I bought the car new and I'm responsible for essentially every one of the 99,700 miles on the clock. The earlier S2000s (1999-2003 model years - called the AP1) are notorious for oil consumption through the PCV valve (for a number of reasons), and as a consequence the intake manifold and throttle body will typically develop a nasty coat of carbon saturated goop. In contrast - the intake and throttle body of my S2000 could only be cleaner if I steam cleaned them (or ran a water/methanol injection system). I credit this product's use, in conjunction with using a top-shelf synthetic oil (Amsoil) with keeping my engine not only clean, but essentially free of wear. The last leak-down test performed on my engine (at 90,000 miles) showed less the 2% leak-down in all cylinders, and no more than 0.5% difference between all cylinders (1.25, 1.5, 1.5, 1.75 - cylinders 1-4). I do not drive my S2000 conservatively either, as it gets revved to 9000 RPM 2-3 times every time I drive the car - and my car is geared with a 4.44 final drive. Those are essentially 1/8th mile gears, and contribute to higher than normal RPMs in all gears, when compared to a stock S2000 - and significantly more RPMs on average than any conventional street car.To give the proper perspective, the age of an engine is not simply a function of the number of miles driven, but as a function of how many average RPMs the engine turns per unit distance (measured in the engines average RPMs turned per mile driven). This is why (generally) a car with mostly 'highway' miles typically has significantly less engine/drivetrain wear than a car with mostly 'city' miles (and why city driving is considered "severe" driving conditions by most auto manufactures). With this in mind, your average Honda S2000's engine turns 1.5 - 2 times as many RPMs per mile as the average passenger car under 'normal' driving conditions. If an S2000 is driven in a 'spirited' manner - that number can be over 2.5 times the average car. So (for example) imagine a Toyota Camry with less than 2% leak down per cylinder with over 200,000 miles on the clock (essentially an engine that is barely broken in) - that would be amazing, and would give a more effective measure of part of the benefit of this product has provided my S2000. So imagine how much your 3 Series, Camry, Accord, Fusion… ANY gas fueled car would benefit from using SI-1 and a quality synthetic oil? It truly does make a difference.You might ask - "how does a fuel system cleaner reduce wear in an engine?". The full answer is complicated, but the simplified explanation is that the the fuel - more importantly the additives in the fuel - provide upper cylinder lubrication (direct lubrication), and the detergent action in the fuel additives is designed to help prevent and remove carbon deposits in the engine. Deposits due to fuel quality and combustion byproducts are a major source of wear in all engines.Most top-tier fuels (Chevron/Texaco, BP, Shell, Exxon to name a few) collectively established a self-imposed convention to supply higher levels of detergents than required by the government (a form of self-regulation). However, these fuels supplied with almost twice the level of detergents required by the government still do not provide enough detergent and lubrication to keep your engine clean - especially with the levels of ethanol pushed by the corn lobbies. As a result, deposit build-up is still a reality facing car owners. While deposit formation is not immediate in top-tier fuels - and most certainly not nearly as fast as with bottom-of-the-barrel fuels (Citgo, Raceway, Sams Club… etc), it will happen over time. This is where SI-1 shines: it provides outstanding upper-cylinder lubrication and cleaning action - keeping your engine almost analytically clean, and it does this without chemically breaking down your motor oil (in blow-by products).One of the reasons this product works better than products from other quality fuel system cleaner manufactures (such as BG and Chevron), is the fact the SI-1's detergent process is more 'gradual', because it's specifically catalyzed by the heat of combustion - and the cleaning process is not solely reliant on strong chemical solvent action. The main components of SI-1 responsible for it's highly effective cleaning process (as mentioned by several other reviewers) are polyether amines (PEA). BG (44K), Chevron (Techron), and essentially most other fuel system cleaners rely heavily on strong solvents (non-polar solvents, of varying concentration and quality) instead of PEAs to remove carbon and other deposits (even though some of these products use low levels of PEAs in their formulation). While the use of quality solvents can be highly effective (again, dependent on the concentration and quality of the solvents used), the unfortunate side effect can be the premature chemical breakdown of motor oil - which is why most fuel system cleaner manufacturers recommend you use their products the tankful prior to a scheduled oil change. How many people are able or willing to schedule/time the last tank of fuel before a scheduled oil change in their busy lives? Not many.You might have noticed I only mentioned two other capable fuel system cleaners by name (products which I believe are very effective "cleaners"). Their specific mention was deliberate. Other than Redline, BG, and Chevron the only other effective fuel system cleaner that I would recommend to anyone would be the one made by Amsoil (Performance Improver - PI). PI works in a similar manner to Redline's SI-1 and contains PEAs, but I have found Redline's SI-1 to be more effective and economical when compared to Amsoil's PI. The vast majority of other branded fuel system cleaners are essentially "snake oil", using ineffective concentrations or mixtures of solvents and carrier solvents (heavy aromatic naphtha, xylene), heavy petroleum products - and in the worst products, they use heavier alcohols (polar protic solvents) in place of more effective cleaning agents. The use of alcohols and some heavy petroleum products actually does more harm than good and actually creates more deposits. Your car may seemingly run a little better when operating with fuel treated with those products - but the car will rapidly run worse once the product is diluted in the follow-on tanks of gas. What does your average person do then? Buy more and add it to the fuel again (thinking it needs a little more cleaning). The car then runs a little better, but then doesn't (again) when the product is diluted… and I think you get the idea. This vicious cycle doesn't happen with a quality cleaner.SI-1 Usage: The best way to use SI-1 is the way it was originally designed to be used - by titrating (mixing) a specified amount per tank (depending on how much fuel you fill up with). I personally use approximately 1/10-1/4 bottle per 10 gallons - using a higher concentration if my car's engine needs more cleaning (subjective decision), or if I am forced to use a lower-tier gas due to low fuel and few to no other options.The instructions on the bottle recommend using a full bottle every 3,000-5,000 miles or so (like most of the fuel system cleaners available) - but not because of a formulation change. The change from Redline's previous recommended per-tank addition of SI-1 to a 3-5k mile interval was pure marketing - because most people are notoriously lazy and unwilling to add something every fill-up, and Red Line's marketing decided to accommodate those too lazy to titrate. While a bottle every 3-5k miles is not at all a bad choice (I occasionally do this to supplement the per-tank titration method), I don't substitute a 3,000-5,000 mile interval for the much more effective addition of SI-1 in every tank.The main problem with cleaning your fuel system only once per 3,000-5,000 miles is the fact carbon and other deposits build up over the interval between clean-ups - and that build-up increases wear over that time. If you're running a conventional or cheap synthetic oil - that increased wear is happening just as your oil is breaking down, compounding the wear problems. Furthermore, treating one tank-full of fuel with your chosen fuel system cleaner once every 3,000-5,000 miles will not get rid of all the cumulative build-up, and the following interval between clean-ups will accumulate more deposits than the interval before the last (and so on).SI-1 keeps my S2000's engine constantly clean as it is driven, and build-up (and wear) has never been a problem. Using SI-1 in conjunction with using a quality synthetic oil (such as Amsoil) is the best way to ensure long life and flawless operation of your (gas powered) vehicle's engine.

Short version:Among all fuel system cleaners I'm aware of, Redline SI-1 contains the highest quantity per dollar (based on manufacturer MSDS) of the critical fuel-system-cleaning compounds known as polyether amines (PEA). Primarily for this reason I believe SI-1 to be the best available and most cost-effective fuel system cleaner product at retail pricing. At the current price per bottle when bought by the case right here on Amazon ($5.30) it is a bargain (12/15/09 edit: the price here has almost doubled since I wrote this and it is now, unfortunately, far from a bargain).In my case it has not been necessary to use Redline's recommended quantity of approximately 3 oz per fill-up. The effects of 1 oz per fill-up are indistinguishable in terms of tested results (see my basis for this statement below). This results in an approximate cost of $0.35/tank or less than a tenth of a penny per mile. A full case at this usage rate is enough to treat 180 full tanks of fuel or to last approximately 80,000 miles. (Figures based 15gal/tank, 25-35mpg).Long version:As far as I know, every effective fuel system cleaner on the market uses a class of compounds known as polyether amines (PEA), in varying proportions, to effectively clean deposits from fuel system components, and particularly from fuel injectors, which can quickly impact engine efficiency and performance when not operating correctly. My understanding is that these compounds were first developed by Chevron and sold under the Techron name, and have since been made available to other blenders of fuel treatment products. Until recently BG 44K, Chevron Techron Concentrate, Gumout Regane Fuel System Cleaner, Amsoil P.I. Performance Improver Concentrate, and Redline SI-1 (among others) listed polyether amines on their Material Safety Data Sheets (MSDS) in proportions varying from approximately 25% to 50%. Most of these products no longer list PEA on their MSDS, having changed their terminology to disguise the precise nature of their products' constituent components. Whether PEA is still contained in those products is a matter of uncertainty. As of this writing Redline's SI-1 MSDS still specifies that the product contains 30-50% PEA. Consequently it is one of the few remaining fuel system cleaner products that undoubtedly does contain PEA in significant quantity.I have been able to test the efficacy of fuel system cleaners in one of my own vehicles using a method I stumbled on after having its injectors professionally cleaned while out of the vehicle. The car in question uses a Bosch engine management system that reports fuel injector data to an on-board computer, which then uses that data to calculate and report instantaneous and average mpg to the driver. I noted after the professional cleaning that the accuracy of the reported mpg, when used to measure average mpg over each full tank of fuel, improved suddenly from a prior error of around -3% - -5% (that is, the reported mpg was ~3-5% below the actual mpg, or typically just over 1mpg low) to an error as close to zero as I could measure (that is, usually between -1% and 1%, fluctuating above and below a perfect "match"). This can be explained on the basis that the engine management system will compensate for a dirty injector by holding the injectors open slightly longer during each combustion cycle, in order to admit the proper amount of fuel. The on-board computer interprets that as a slightly higher rate of fuel consumption, reporting a lower-than-actual mpg figure.After several thousand miles - not long - the perfect mpg accuracy I'd noticed began to deteriorate, likely indicating that the cleaned injectors were beginning to suffer from some sort of renewed impedance to fuel flow. Out of a desire to retain near-perfect injector performance, and also out of curiosity, I started experimenting with various commercially-available fuel system cleaners and keeping records of the results at each fill-up.Leaving out the long details, I'll simply say here that the results were surprisingly clear and unambiguous. Each time I went several tanks without using a fuel system cleaner (usually as a result of simply forgetting to use it or not taking the trouble), the on-board computer (OBC) accuracy would deteriorate. This would fluctuate from tank to tank, of course, as a result of inevitable measurement errors, but the trend was very clear even over a small number of fill-ups. Returning to the use of a fuel system cleaner (Chevron Techron Concentrate, Gumout Regane or SI-1, all of which at the time did contain PEA), the accuracy would improve again very quickly - within 2-3 fill-ups. I began using the SI-1 exclusively seven months ago based on its apparent cost-effectiveness and since then I have reduced the quantity I use in each tank to the current 1oz per ~15gal fill-up. The results remain unambiguous. If I use this small amount of SI-1 consistently, the accuracy of the on-board computer is excellent, with an average error of below 1%, or a fraction the error rate seen when not using such a product.Based on the above I feel I can confidently conclude that SI-1 works very well, even at reduced treatment rates, at keeping fuel injectors clean. Fuel system types and injectors will vary, and other parts of the fuel system - for example intake valves and combustion chambers - might benefit from higher treatment rates (or, conceivably, might not benefit at all). Actual engine efficiency will not vary nearly as much as injector cleanliness, since the engine feedback system normally corrects for imperfect injector flow rates. However, as the flow is more greatly impeded, or impeded differentially among the individual injectors, mpg will be affected to some degree. I feel it is well worth the tiny cost to consistently use a small quantity of SI-1. Other benefits, such as to combustion efficiency as a result of combustion chamber cleanliness, to volumetric efficiency as a result of intake valve cleanliness, and to fuel system lubrication, probably exist as well although I can not evaluate them and have not attempted to do so. Other fuel system cleaners may work as effectively, or nearly as effectively, but I do not believe them to be as good in terms of value per dollar spent.In my experimentation I did try some less expensive fuel system cleaners, those not containing PEA. They appeared to have no effect. I can not categorically state that only PEA-containing fuel system cleaners work, of course, but my observations did match the conventional wisdom on this point. I also experimented with using top-tier fuels only, without any additional fuel system cleaners. The results were the same as when using non-detergent (Costco and others) fuels. I don't doubt that top tier fuels contain small amounts of cleaners and will keep a fuel system functionally and acceptably clean, but the quantities involved are reputed to be tiny and my observations seem to indicate that even a small amount of additional additive is far more effective.

I don't know of much of a way to know if this stuff really works on my car, but I have seen photos on ads. I take good care of my cars and want to do the best by them, and keep intake parts, injectors, and etc clean. It may be totally mental on my part, but I like the idea of continuous use, rather than only every 3000 miles, which is most commonly recommended for an injector cleaner. Other brands are quite difficult to use smaller amounts on a continuous basis. This seems more oil based rather than a harsh solvent like some others, which I like. I have used this for years and never had a problem with injectors. I do use this brand, though, while holding my nose, because the techy had refused to talk to me, hung up on a phone call, when I wanted to help him understand how his recommendation on another product destroyed my motorcycle engine. My intention was only to help him, for the next customer. Mostly this brand is high quality.

This is the best Fuel System Cleaner I have used in 30-years. Trust me when I say I have used them all. I take care of my vehicles with proper routine maintenance however, and I switched to this product back in 2005. One at oil change and 1500 miles each (4.5K oil change), our vehicles run great, start instantly, idle smooth and get expected mpg well up to 200K. Is there better, well possibly but it works better than anything under $10/bottle so why waste your money? First time using any cleaner and more than 50K miles? Buy 3-bottles, first full tank use 1.5 bottles, 3rd full tank 1.5 bottles, huge difference in the way the vehicle runs overall. It also doesn't hurt to use Tier-1 gasoline folks, there is a difference, especially if your running a new direct injection fuel system on your new car. These systems are notorious for carbon build up.