Originally Posted By: tig1
Fuel may be the big problem here. Your FF is very low, in fact I don't remember seeing one like this. With only 40K on this engine you may need to go to 3K OCIs to make this engine last.
Fuel has been my biggest issue so far. For all of my Dyson analyses, except for the last, fuel has been > 1%. What may be the issue is the off-the-shelf map that I’m running. The stock map doesn’t drop AFR’s down substantially until well after the onset of boost, most likely for emissions reasons. Cobb’s map drops AFR’s down to 11:1 immediately, which could be (read: probably is) the source of my dilution. The strange thing here is that I changed my oil the day after driving 65 mph all the way down from Boston to New London without boosting at all. Part of the fun of the off-the-shelf map is that it comes with boost-select for the SI-drive system. I selected the mode with lowest throttle input and target boost, which consequently left me in vacuum (and higher AFR’s) for the duration of my trip down and while driving to the hobby shop to change my oil.
This report shows that I can’t take Amsoil (at least the SSO 0W-30 flavor) nor T6 out this far and have it hold up. I tried the same with T6, as shown above, and it was beat all to heck, too. As soon as I backed down to ~5,169 miles with T6 all was well, and I experienced the lowest fuel dilution so far.
My guess is that extended drains MAY be possible during warmer months, but are darned near impossible (at least with these two oils) during the colder, fuel-diluting months…maybe not, and maybe I’ll end all of this UOA shenanigans and stick with T6 at 4-5k intervals with nary a worry.
Originally Posted By: INDYMAC
This looks pretty good to me, considering the severe driving conditions. Was the T6 driven under similar conditions? Where is the AG wear coming from? I don't normally see that. Fuel% looks pretty good for your 5 mile commutes at slow speeds to work under frigid conditions. That's a lose/lose situation even under warm climate conditions. It handled the 7.5K OCI just fine...no engine damage.
I agree with the no engine damage assessment, though I’m still going to back this next interval down to 5,000 miles, even though it should be better with all of the warm-weather driving. It seems like such a waste to drain Amsoil so soon, but all well. The T6 represents all of the previous samples except for the very first one, which was Cam2 5W-30. That’s on the above set of UOA, and you can follow it by date and mileage.
Originally Posted By: demarpaint
My monitor sucks, but if I'm seeing this correctly, the interval was only 6 months, and 7,477 miles? If so I would not follow Amsoil's severe service recommendation of 1 year or 15,000 miles, you'd be asking for trouble. OTOH you changed it at the right time if the oil was in use for 1 year. Then the oil held up as Amsoil claims.
6 months is correct. I meant to change it at 6,500 miles, but got extremely busy.
Originally Posted By: dparm
270 flash point? Yikes.
I saw that, too. That’s worse than the worst T6 showing. However, this is the worst weather (winter) the STI has been through, being only its second winter as a DD. The first one it stayed parked while I drove my old Legacy. Unfortunately, I ended up giving my DD away to a relative who smashed her car, so the STI became my DD.
Originally Posted By: Gene K
I dont know how much faith I would put in that 1.73 Fuel Number. That looks like a good bit more fuel than that. The fuel looks to me like its starting to attack the oil and bearings to me.
Is it enough to cause damage? I dont know but I do know if I saw numbers like that after 30,000 miles on one of my diesels I would be concerned.
What do you mean? You don’t trust the number itself or having such high fuel dilution in the sump? The numbers shown here, at these levels, don’t concern me at all. I’m not going to say that the results were good, nor that I plan to run it this long again, but I don’t believe that my engine has suffered.
Besides, Subaru says it’s ok to run 7,500 mile OCI’s using synthetic oil. What do you guys think about that? Ha!
Oh, and thanks for all of your comments every one. It may seem like I'm pretty set in my ways when it comes to wanting to extend my drains, but I'm very appreciative of all your input and advice.
