I have to disagree with Cheesepuff. If using Walmart oil, use a Euro oil (Castrol 0w40, M10w40, QS 5w40, even Pennzoil Euro 5w30…in that order. Don’t know about Valvoline Euro if your Walmart has it). Castrol Euro 5w30 or Euro 5w40 might be OK, but deserve to be called the “Walmart end” of the Castrol Euro product lines.
I still think Amsoil and HPL are generally better, but you have to choose the right one.
@Orangepeel do I have this right: you replaced the Amsoil 5w30 Euro with one of the Amsoil 5w40 Euro’s? I wish Pablo had maybe directed you more specifically than just “stick with Amsoil.” If that’s all he did, that wasn’t particularly helpful.
I’m still puzzled by the low viscosity with the high flashpoint in your Blackstone UOA in the other thread. It’s possible a retest would have been justified. They might have botched it. But again, I would switch to Oil Analysers, for your UOA’s or someone else who does gas chromatography, and look for fuel dilution, and keep your 100c viscosity above 10.5 or better yet, 11. If indeed you switched from 5w30 to 5w40 Amsoil Euro, that should do the trick, but so should Amsoil Signature 0w40. I know local Subaru places here would suggest Motul, but the right grade of Amsoil should also be great. I’ve lost track of the various Motul’s, don’t know which is best for direct injected turbo motors, but one Subaru tuner shop here swears by it, as does another track-oriented shop.
My EJ25 is not tuned, and I don’t track it, but I have been known to get on it now and then. I disagree that the EJ engine is more fragile than the F-whatever. Too many random tunes and overstressed driving give it a bad rap. I found Castrol Euro 0w30 to be the best Castrol, with 0w40 Euro being 2nd, but that’s just as unobtanium now. For that matter, Castrol might have “watered down” whatever made their older 0w30 so great. iMHO, the Walmart flavors are lessor. I was going to move to Amsoil or HPL, but couldn’t decide which. I have a small stash of each brand, but all thinner than what I would like to put in the EJ25. Both brands have lots of options, and HPL can get quite pricey. I tried the QSFS, was not that happy, but admittedly, I DIY blended their 5w30 QFFS with their Euro 5w40 as I thought I was going to sell the car within a thousand miles. That didn’t happen. Since I still have it, and found the Castrol 0w30 online, I switched back to it…motor seems quieter, smoother, happier than with the QS. I UOA’d the QS, and it wasn’t terrible, but I still felt like the Castrol and my engine were happier together. The QS lost more viscosity and the iron reading was noticeably higher (my iron was always below 10ppm with the Castrol’s despite running for 4700-5000 mile yearly OCI’s.
***EDIT*** I should probably delete much of this post, but maybe there is still some slightly useful info in it. I keep going into “advice mode” which usually gets me in trouble, and I try to refrain….but I slipped again.
BUT: it would be great if
@Orangepeel could clarify a couple things: the other thread came later, and said the UOA was for Amsoil 5w30 Euro. Here, in this thread, he said Amsoil 5w40. In neither case should the UOA 100c viscosity be 9.38, unless significant fuel, or serious shearing (which I would have not expected with Amsoil, though I’ve never used their Euro oils).
Also where are you located? It may not matter, but if you live near Death Valley, recommendations could be different than if you live near Ankorage or Banff.
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