Edmunds Answers



  • karjunkie 05/11/10 9:02 am PST

    This old wive's tale has been going around for years. You can ALWAYS mix different brands as long as it is the correct viscosity AND API rating required for your car. This is factored in as every manufacturer understands you can be low on oil in many places that will not have your particular brand. The API Rating is equally important to viscosity, as it shows the blend is specifically appropriate for the engine. Of course, every brand tries to use a different mix of additives to distinguish itself, but in the end the API rating is what counts. API stands for American Petroleum Institute. API sets the industry standards for passenger and commercial vehicles. These standards are recognized, and in many cases, developed in conjunction with car and lubricant manufacturers. The letters next to API, such as SM, refer to the quality level of the motor oil. In the case of SM, it’s the highest available standard for passenger vehicle. CF is a diesel engine or commercial vehicle standard and the highest current one is CJ-4.


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