Date registered: Nov 2008
Vehicle: 1981 300TD 310k--1966 230 165k--1970 280se 172k
Location: Ohio City, Ohio
Mentioned: 1 Post(s)
Quoted: 33 Post(s)
With these old engines having flat rocker arm surfaces, I've come to the conclusion that modern oils are unsuitable due to the lack of phosphorus and zinc, which help the oil to cling to metal surfaces after running.
You can find these additives and add them to modern oils if you like, or use a diesel oil (like Rotella 15-40). That's what I use in both my 300TD and my 230 fintail. That's a fine oil and available nearly everywhere.
There is a lot of reading on the subject. Search for phosphorus zinc and you will learn about it.
1981 300TD--310k miles
1970 280sel--172k miles
1966 230--162k miles