A. Many lubricant consumers refer to the basic engine manufacturer approvals and API credentials to determine whether or not the oil selected is suitable for service and complies with component manufacturer recommendations.However, many oil brands provide several products within their product lines that may all carry the same API credentials as well as engine manufacturer approvals.An engine oil manufacturer may offer several heavy-duty engine oil options, all listed as API CJ-4, with all the same engine manufacturer approvals or recommendations. The confusion comes when attempting to differentiate whether or not there is true performance advantage in the number of options within the brand. The scope of this message cannot provide all the details needed to offer an adequate response but here are few basic comments:a. What a heavy-duty engine oil is listed and licensed at is not the only thing to consider. The testing and certification process can produce different performance results. For example, a test used to qualify CJ-4 oil can have as much as a 50% variance in allowable passing limit versus the "headroom" performance that can be achieved with premium additive technology. Why is this important? It may not be for some equipment owners unless you need optimum engine life, operate in severe conditions or need longer service life out of your engine oil.b. Oils also can be further tested in real operating conditions or in real-world fleet conditions. This further shows an accurate level of performance by providing real-world field testing results. This, combined with engine teardown inspections at extended mileage levels, provides another level of evaluation. Premium performing oils will show outstanding results versus oils that are produced just to meet minimum passing levels.c. Before buying an oil at face value that it meets all the credentials, an equipment owner should at the very least ask a supplier specifically what level of performance confirms and supports the advertised claims.
For example, the API provides a list of licensed and registered engine oil products.