Looking at the math, what I saved on oil and filters in the taxis by doubling the OCI and sticking to conventional was significant. Going to manufacturers recommended OCIs and synthetics for "cheap insurance" would have bought each taxi a brand new crate engine at the end of their service life, which wasn't needed anyhow since the engines ran fine while everything else was falling apart.
Plain, simple Garak.
2008 Infiniti G37 coupe - Mobil Delvac 1 ESP 5w-40, Wix 51356
1984 F-150 4.9L six - Quaker State GB 10w-30, Wix 51515