I have researched this to no end.....OIL. FWIW i have a 93 Civic with 280,000 miles on it that burns 1 qt every 1000 miles. I have not changed oil in it for 55,000 miles. I DO change the filter every 6-10,000 though. List of oils I have used for top offs. USED 20w50 motorcycle oil, USED 5w20 from wifes Odyssey, 75 90 GEAR OIL,Non-detergent SAE 30 weight, ADvance Auto oil, Synthetic , Rotella 15w 40 Deisel,PEAK, QS, Pennzoil, Castrol, Havoline,Valvoline, Generic stuff Menards sells, STP, 10w30, 5w30,etc etc. Anything and everything. IT looks BRAND NEW inside the head. No exaggeration. BRAND NEW!!!RUNS like a champ on any oil. Not even a tad of varnish,crud, goop, looks like brand new metal straight from the casting.You'll be fine with whatever meets specs.Or in my case youd be fine with whatever is oily....key is frequent intervals of lubrication. Dont waste your money on AMSOIL or Royal Purple or whatever the heck else marketing ploys for engine/trans protection is out there.