hi all,
i'm the guy that shpankey posted on behalf of. i greatly appreciate all of your thoughts and insights with this matter - Bitog is an extremely helpful place!
just to put it out there - my car is a 2008 Mazdaspeed3 with approx 53k miles on it. it has basic modifications - intake, intercooler, downpipe, tuning, diverter valve, upgraded fuel pump, and colder spark plugs. compression test less than 5k ago gave 180psi across all cylinders with spark plugs looking good.
regarding the seafoam - it's a common approach for these motors. the direct injection setup results with gunk in the valves, intake runners, etc. i'm pretty sure someone has 'scoped it before and taken pictures, but no idea where they are. it's the same as what's experienced in the VW 2.0T DI motor. here's an example:
regarding idling - i have allowed the car to warm up for 10-15 minutes on a few occassions, mostly because it was below 0* and i prefer to give the engine/turbo time to warm up. i can cut this out no problem, seeing the effect it has had on my fuel. it's just a matter of staying out of boost until the engine's warmed up.
regarding fuel dilution - i've seen the fuel % in my oil drop from 1.5% to 0.5% from one analysis to another simply from one highway run. i was up near 2% when i started doing analyses, and highway burns have kept it below 1%. wear on the motor has not been affected by the dilution (per blackstone...)
regarding the sodium - the lack of potassium implies that it's not coolant. it's been less than 10 for most analyses so far, so the increase is not easily explained. yet the first suspect is coolant and i have not lost any. i checked it, saw that it was 1/2" low, filled to "Full", then checked a couple days later and it was a 1/2" high. engine was warm both times. not sure why that occurred.
a note regarding fuel/sodium - i've been going almost exclusively to a Murphy Oil station here in iowa for gas, bc it's the only one nearby that has 93 octane. i'm not sure if they've got sodium in their blend.
regarding the fuel dilution - the four main variables that have changed have been that i've replaced my fuel pump (had an upgraded one but it failed), it has been a very cold winter (idling...), i've been getting gas @ one place, and i did NOT do a highway run prior to this. also, lately i've been avoiding cruise control, meaning my speed/boost/fuel varies on the highway.
typical stock fuel pumps on this motor (cam driven) deliver 1600-1700psi fuel at WOT. mine is giving 1800+psi, which probably is scaled through the rev/throttle range.
i believe i can resolve the dilution issue by cutting out the idling, doing more highway driving w/ cruise control, and doing highway driving before my next drain.
then, for the next drain, i was going to run the 6qt i still have of amsoil and wait for the analysis to come back. if it's still bad, then it's rotella t6 and 3-4k intervals for me, at least until things look better; it may need to be what i do for the winter. i had EXCELLENT luck on my 1.8T GTI with Amsoil, and the oil is doing its best with my fuel in the MS3 and still holding up, giving decent engine wear. i did see T6 @ the local auto parts store today.
the main question mark for me is the sodium. i saw an STI UOA on here with 200-300ppm, which is WAY higher than my 20-30ppm. i did NOT seafoam on my last change before this most recent one, which also had the sodium, so seafoam is probably not the source... i did seafoam at 42k, though. i am tempted to blame the fuel but i've read that sodium is not used in gasoline.
overall, my car is running well. i do not have any operational issues, and i am not losing coolant nor oil. should i do a leakdown test? i am not sure if it is necessary.
