The Right Oil
Dude, I run only Synthetic, But Amsoil Is Crap, It's all Recycled Synthetic, (i.e. A Castrol, QS, Mobil 1, Penzoil Slurry) and anyway you slice it thats not good, you may as well be going to Mr. Lube nd getting that Bulk 5w20 Shit, I have Also used QS Horse Power, Although this may be good in Ferrari's, It's Crap in Kia's, Significant Reduction in MPG, and on Next oil Change It was fine, though I thought it might be the Oil Filter, so I Tried again 5000 Later, Same thing Happened, With Diff Oil Filter, so I strongly advise against Both Amsoil and Quaker State: Horse Power, Both are no good, I used to Use Castrol Syntec in My Miata, I had no Complaints With it... And Very Few With it in My "Rio". However the one that I do Recommend is Mobil 1 0w20, I have Noticed a Major HP, and MPG Diff with this, Mobil 1 Has even started to Manufacture a New Syn formula that Guarantees A Higher MPG!!!
I go 5000 Between Oil Changes though, I could go as High if not Higher than 10K but I really Would rather not Chance it.
anyway those are my Recommendations