OK, I've enjoyed my fair share of crow from my original reply earlier in this thread. Normally this topic sparks a bunch of garbage, but so far I see some reputable guys chiming in with some logical, knowledgeable replies. I'm still running the XPS synthetic blend in my ETEC, but that's because that's what DOO recommends. I like the low usage and low smoke though too. I feel like I need to stick to it at least until the warranty runs out. Then, we'll see.