When I had a 1985 Mercedes with the om617aTD 5 banger turbo diesel, I bought 2 gallons of warren 15w40 and a STP oil filter at autozone. I think the oil was called lubriguard.
Delo 400 SAE 30 from the AZ closeout of way back when, gallons & gallons of it, none for more than 99 cents/gallon, a couple for ONE CENT a gallon! Way back in 2004, it was BITOG that turned me on to it, used the last gallon about 2 years ago.
Rotella T 15/40. It was what my dad ran in his OTR big rigs and so that’s what I ran in my 6.2l and 7.3l diesels. Still using it in my ‘02 Powerstroke, 2 tractors and ‘51 CJ3A.
QS 15w40 in use in the Ford 2.0 OHC gas engine several years ago. I remember the engine was very quiet on this oil. Can't remember the exact spec on this QS oil but it was a HDEO oil.
Proven to provide exceptional wear protection1 and improved piston cleanliness2
www.shell.com
that was for a Fiat diesel, that I miss so much.
Then Rotella T6 0W40...to use in various gas engines. Currently using what I believe is the John Deere version of the T6 in my Mazda, good winter starts here in Canada.