I've mixed blends of Rotella 15w40 and Formula Shell 5w20 (Dino), PYB 5w20 or QSUD synthetic 5w20, Chevron Delo 15w40 and Havoline 5w20, Mobil Delvac 15w40 and Mobil EP 5w20 or Advanced Auto 5w20 Synthetic for many of the oil changes that I did last month and early this month.
The mix was usually 50/50 or 60/40 of Diesel to Dino or Synthetic auto oil. I used NAPA Gold, P1 and Purolator Classic Oil Filters for each vehicle. I tried to oversize the filter if I could find the application conversion.
All the Family, Neighbors and Friends vehicles are "Gasoline" engines. All of the Diesel Oils were API-SM, CJ-4 rated and all of the vehicles were 2006 and earlier.
When I get back to Coney Island I will change my oil to a blend of Shell Rotella, Triple Protection 15w40 and Formula Shell 5w20 all in API-SM. I plan on using 3 quarts of each in the sump for a 6 month run.
Lots of Stop and Go traffic and short trips in NYC so this blend of oil should help clean the engine and give them added protection. I've had nothing but compliments from all of these people about how their cars, suvs and mini vans are running.