I've been reading some posts about this additive. In the past its been less than Redline. I'm primarily interested in boosting the Cetane level since the various diesel stations most convenient to me seem to have a varying degree of fuel quality (fuel mileage changes).

What should I be paying for this fuel additive and does it come in different configurations?

After doing the math, does it pay for itself in better fuel economy? (I'm skeptical of this holy grail)

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)