I know fuel additives like STP‘s Octane booster (don‘t complain about them I know they aren‘t all that), I know they can seriously f*ck up more modern engines. But I have a 1987 BMW. with an inline 6 engine. I am wondering if the Injector cleaner, octane boosters, etc fuel additives will damage anything.
The previous post is partly correct. Octane booster - stay away from it unless you have an actual need to boost the base octane level of the gas you're getting. For example, I have an LT1 that's been built to just barely run on super. If I get one questionable tank of gas, it'll knock - I need the octane boost in that case to improve the quality of the gas mix in my tank to keep my engine out of knock. If you add too much of this for an engine that runs fine on 87 octane, you will see strange things like engine run-on, where the engine will pre-ignite off of hot spots, even with the ignition turned off. But otherwise, octane boost is a waste of good money for most engines. Fuel injector cleaner - good for the occasional use. The cheap stuff is mostly ethanol, which is actually good to help remove water from your tank, but not so good on the hoses of an 87 bimmer, since they were built before ethanol was a major additive. The more expensive stuff is mostly solvent and detergent, which won't harm a thing unless you mix it well in excess of what the label says. Most all gas additives (and most oil additives for that matter) are now designed to accommodate modern engines and sensors. I've used fuel injector cleaner with great success on both a Jeep Grand Cherokee and a Toyota Tacoma that were experiencing poor fuel mileage and power. Do I use it with every tank? Heck no! I'd only recommend this occasionally, just as a little kick to help keep the injector patterns correct. If your injectors are shot or really clogged, they will do nothing to help you. In short - forget octane boost, and be careful with the ethanol/methanol based cheap supplements on an older car! Even on the good stuff - use it sparingly.
These things are a waste of money. Octane boosters are not the same and are real. Gasoline already has additives and ethanol is known to cause problems in boat induction systems. My fear is that if you do have any varnish in your older tank that the additive might knock it off and plug the fuel filter which should have stopped anything larger than few microns from getting to your injector anyway. Fuel system cleaning at most service centers are largely an income generator with no real benefit unless they are actually cleaning the intake. Most of these shops disconnect a vacuum hose and put cleaner through it. As this path is not through the injector anyway it is of little value.
Like all things---some good , some fake. I have tried many additives in many different engines. Some actually do work. Others worked under certain conditions. Example- fuels with a lot of ethonal got better mpg when I used Lucas When I got good fuel I saw no difference. In our m/h one diesel fuel additive consistently improved mpg by 15 to 20%, is cost effective. I go by miles per dollar,not mpg. I am 70, have experimented with additives a lot.
