The E30 manual specifically states that such products are unnecessary. I've used them in the past but I'm wondering if they are not such a good thing in the long run.
They are a good thing. These things are modern products which substantially remove engine deposits. They don't need to be used all the time, but once in a while is good. Gasoline manufacturers are now putting a lot of that stuff directly into the gasolines. They are refered to as "Top Teir" fuels. "Top Tier" is a standard set by the car companies a few years ago for the oil companies to achieve. BMW was heavily involved in setting the Top Teir standard. http://www.toptiergas.com/deposit_control.html Most of the major oil companies have achieved Top Teir, the most noteworthy exception being ExxonMobil, who says they like doing things their way.
Is there any indication that Exxon/Mobil's gasoline is inferior to those who subscribe to top tier standards? Would you say using something like Techron once every 10 (15? 20?) refills is adequate?
There probably is some independent testing posted somewhere about ExxonMobil performance. I've never seen it. Top Teir is good because it also guarantees a technical specification for performance. Apparently Techron does remove old deposits as well as prevent new ones, but I don't know how often you have to use it to keep top performance. There are so many variables its probably a question with as many answers as how often you have to change your oil.
I have used Red Line's Si-1 injector cleaner in every BMW I have owned with great success and never any issues.
A long time ago, back when I bought my E30, I was using the local gas station, not a major brand (Freedom Fuels). After a while, I decided to try out Shell as I have heard about how good it is. Well, after a while of getting gas at Shell, I felt the butt-dyno tell me that the car is running a little better. It didn't feel as smooth before when I was getting gas from Crappy Fuels. So, I've been using Shell ever since. Only once have I used Techron and that was to try to diagnose a problem I was having. I didn't notice any difference, but that's probably because I only used it once. I personally don't think there's much that Techron offers over what Shell has in their gas, at least from my singular experience with Techron. Now Shell has put some kind of nitrogen whatever in their gas. We'll see how that affects the engine, but I don't get a strong feeling that it's going to do anything more than what it has been doing up to this point.
I typically use Shell fuel regularly but toss in a bottle of Chevron Techron Fuel System Cleaner about every 10k or so. Or I use the BMW Fuel System cleaner (which is the same stuff just with the BMW brand on it) when my dealers tosses me a free bottle. Best advice I can give is always use Top Tier fuel when possible and avoid (hard to do lately around our area) any Ethenol blends.
I've heard that the best time to use Techron is right before an oil change because of its 'detergent' capability. Anyone else heard that?
I heard that many years ago when the various fuel system cleaners first came out but haven't since then. Perhaps it had something to do with old dino-juice (non-synthetic) oil that was common then?
Why would it matter when you pour it in (when speaking of an oil change)? The gas and oil don't ever mix, do they???
My guess would be that whatever the Red Line flushes out of the engine ends up in the oil, which would soon would be changed. Techron is a more powerful agent than, say, Red Line SI-1, so that much more is eliminated from the engine. This is from the Techron website and it shows what gets cleaned inside the engine: Capabilities Techron Concentrate Plus Leading Competitor Cleans carburetors Yes Yes Cleans fuel injectors Yes Yes Cleans intake valves and ports Yes Yes Cleans combustion chambers Yes No Restores lost power and performance Yes Yes Lowers emissions Yes Yes Relieves cold startup problems Yes No Reduces deposit-related engine knocking and pinging Yes No Cleans sulfur deposits from gas gauge sensors Yes No Protects against fuel system sulfur deposits Yes No Protects gas gauge sensors from malfunctioning Yes No Contains PEA chemistry Yes No
Piston rings don't seal 100%, that's where many of the contaminants in oil come from is the combustion process.
I use to use Red Line's SI-1, but you have to be careful not to over use it. You can run the risk of damaging rubber seals in the fuel system, like at the injectors, if it is over used. But that might be true of any fuel cleaner. I now use BMW's fuel system cleaner about once a year in my BMWs. Full bottle to one tank full of fuel, then drive like hell for that tank! I always use top tier fuel, mostly Shell.
My engine spun a bearing within a few months after starting to use the Red Line product. I didn't use a lot of it -- maybe one full bottle one time and small doses several more times. I have no idea if it would be possible but Is there a conceivable scenario that could have led to the spun bearing from using the engine enhancer? Say, if certain seals were already degenerated?
I don't have the intricate knowledge to say for sure, but I would say the two are probably unrelated. The fuel system and oil system are completely separate with almost no interaction between the two if your engine is in good condition. Yes fuel and exhaust can blow past the pistons, but I don't think it would be enough to degrade the engine oil enough to cause a spun bearing. Any others have thoughts?
There is no way the use of Redline SI-1 injector cleaner was related to the spinning of the bearing, that is generally a wear and or oil failure issue.
