|
Oil Man has it correct out of all that have posted, at least what I have read.
First, ALL fuel comes from the same bulk tank farms and is graded by octane. Any additives above what is required by law for highway use is done either in the truck transport or at the station when it is delivered by the driver. I have watched at the port and all fill up at the same bulk tanks.
Next, while top tier fuel was an excellent choice for older port injection engines as the fuel constantly washed and cooled the valves keeping them clean and deposit free, no fuel touches the intake valves back sides where the coking takes place any longer with GDI engines (except the few that have added in small port injectors in an attempt to slow the coking rate, but so far these all show coking nearly as severe as no hybrids, but is far from a fix.
So, what is top tier doing for these new GDI engines? Absolutely nothing except possibly helping injectors stay clean, but at 2,000-3,000 PSI there is not a very high incidence of "dirty" injectors as in the past port injection engines operating at 45-55 PSI.
|