Got Diesel wrote:
Going down??? Not sure I like the tone of that but maybe it was poorly expressed. The link quoted will not protect you if the ECM has been opened, let alone modified.
InMotion I think said the same thing I did, maybe a little more detailed.
As for the B20 doubt the average tech or Service Manager could smell or tell the difference, but yes it is a chance you take for having a warranty voided. If you have blown a piston and D/C ask for a oil sample test your had, if however you have a IP failure the only way to know for sure you used B20 will be a fuel test at a lab. That is not to say the individual dealer may or may not request one, generally all they do is pump some fuel into a clear container and look at it, seen it done many times. Last time was Thursday. If you have bought bad fuel at a local station then you have recource with the fuel provider by federal law however you might be out the $$$ first then be reimbersed.
I have seen D/C kick back warranty repairs to dealers on parts returned to them because they were signs of abuse or tampering. Local dealership is about to have some really big problems shortly just due to allowing none certified tech's do work on some vehicles and possible ECMs that were tampered with, the SM for that period has already gone elsewhere for work. Worst case of kicked back warranty I ever saw was $97,000 for a one year period of repairs at one of the smallest dealers in the country.