I've been reading Corvair Oil Article by Richard Widman and I see that he recommends using CI-4 diesel oils because they contain sufficiently high levels of ZDDP to protect older flat tappet engines.
Having had a look at the specifications of many diesel oils, I see that they have both CJ-4 and CI-4 ratings. Using Valvoline’s Premium Blue Extreme Engine Oil as an example, they specify:
Originally Posted By: "Valvoline Premium Blue Extreme Product Specification"
In addition, the product meets API CJ-4, API CI-4 Plus, API CI-4, API CH-4, CG-4, CF-4, and CF / SM specifications.
When the oil has both CJ-4 and CI-4, does this mean that this oil protects flat tappets like a CI-4 but uses additives that don't foul catalytic converters or particulate traps?
Having had a look at the specifications of many diesel oils, I see that they have both CJ-4 and CI-4 ratings. Using Valvoline’s Premium Blue Extreme Engine Oil as an example, they specify:
Originally Posted By: "Valvoline Premium Blue Extreme Product Specification"
In addition, the product meets API CJ-4, API CI-4 Plus, API CI-4, API CH-4, CG-4, CF-4, and CF / SM specifications.
When the oil has both CJ-4 and CI-4, does this mean that this oil protects flat tappets like a CI-4 but uses additives that don't foul catalytic converters or particulate traps?