Motor oil question
 

Does any one know how to tell if a motor oil is diesel rated by reading the label on the side? i think it is SJ something but am not sure. also i currently use 15-40 in my engine and wanted to go up to 20-50 because of high miles, i live in CA and have 301000mi on the engine any suggestions on the oil, normal driving conditions.
thanks

The newest designation is CH-4 (C for compression) for diesel engine oil. You can find this on the 15-w40 weights of Delvac 1300, Rotella, Chevron Delo 400, and others. The best CH-4 oils are the synthetics such as Mobil Delvac 1. These are generally 5w-40 weight.

"C" for "Commercial" and "S" for "Service"
 

Actually the "C" in CH-4 stands for "Commercial" and the "S" in SJ stands for "Service". It is a misconception when "C" is referred to as "Compression" and "S" as "Spark."

See publication by API at

http://api-ep.api.org/filelibrary/ACF1E1.pdf

Your right. It is easier for me to remember that Commercial means diesel engines by associating it with compression and that Service means gasoline engines by associating it with spark.