Got 1L 5W30 Synpower SN oil left. I only got this jug due to a sale a while back and now I am stocked up with SOPUS oil - PYB, Motomaster F1(similar to Formula Shell) and PP. What should I do with the leftover? The add. pack seems to use sodium as the cleaning agent while SOPUS focuses on using calcium and almost no sodium. I'm not planning to buy more synpower or valvoline soon due to current stockpile. I have two candidate to put this 1L in. 98 Civic D16 engine that takes 3.3L. Currently has Synpower, want to use PYB next. 01 RX300 1MZFE engine that burns roughly 1L in an OCI when it runs on the highway(my guess). Currently, running Motomaster F1 and no consumption yet for 5K km. 1. Mix Synpower with PYB and use in next OCI on Civic in 2 months or so. Synpower will comprise approximately 30% of total capacity. 2. Dump it into RX300 as makeup oil if it happens. Although, I have leftovers of Motomaster too after each oil change. Which path shall I take?