Fuel characteristics and treatment
UFO - The problems in engines with using too little are far more severe than too much.
Yes, but, that doesn't change the fact that it is best to use just what is needed. Take by analogy engine oil which contains a number of additives to achieve a variety of properties like keeping solids in suspension. While that's good, engine oil is still manufactured with what is needed to achieve a desired performance because too much of those same additives will cause their own problems.
Plus 3 Golfer - It seems to me that if the standard were 460 microns like in Europe instead of 520 microns then the additive package should target to increase lubricity to around 400 microns which IIRC is what Bosch would really like to see.
One of the impressions I received talking with Conoco Phillips was that the target of 460 meant applying a margin relative to this to account for the variabilities involved, hence typically seeing values below this (e.g. the 413 mentioned from testing in the Denver area). This strikes me as similar to the situation with regard to sulfur levels. The limit is 15 ppm, but to avoid exceeding this margin has to be applied to account for the variabilities in fuel production with, from data I've seen, typical values being 10 ppm or less.
tditom - ...the only thing i would be concerned about is that unless you have something in writing from them, or a publicized document from them making those claims, then you can't rely on them continuing to beat the standard set by ASTM.
That's right, there are no guarantees (are there ever?), but there are reasons to have confidence, including a fuel manufacturer's reputation and their business motivation to maintain that reputation.
securityguy - You don't gamble with your health and your property so why gamble with your car.
Actually, people gamble with their health and property all the time, but we know what you mean. Still, take the health analogy - nutrients and medicines may be good, but too much of almost anything is bad.
I'm not arguing for or against additives, but just as the variability in fuel lubricity from the pump is a concern, there is quite a bit of variability involved with treating at the time of fueling. Talking with the fellow from Innospec gave a much different impression of how ULSD is treated. It's not just a matter of throwing in additives at the terminal. Instead it's a process that is integrated into the fuel manufacture, taking into account varying properties of the raw ULSD, temperature and other factors, and the end result is monitored to provide feedback to the treating process. This is normal practice in the modern manufacture of fuels, lubricating oils and most manufacturing processes. When you treat at the time of fueling you don't know the characteristics of the fuel you are treating and you cannot predict the fuel characteristics that result. And, while the risk of too many additives may be less than too few, it does have a risk.
In the end the ideal situation is to have a fuel you have confidence in. Heck, I admit I'd prefer to not have to bother with pouring in additives when I fuel (and indeed, I'm not at present, the last time I did was 40 years ago with a 2-stroke SAAB - but I digress). I do think that one should realize that treating at the time of fueling is not guaranteed to eliminate risks and does potentially entail possible risks in itself. There's a lot of focus in this discussion about lubricity, but that is only one of several fuel characteristics that are important to our fuel systems, and then there's the exhaust system with its complex chemical reactions.
2009 Jetta TDI DSG
