Very few 5W-50 motor oils are suitable for the ultra-high-performance Ford Mustangs such as the Boss 302 or the Shelby GT 500 with the supercharged 5.4L or 5.8L Trinity engine. It used to be that Castrol Syntec Synthetic 5W-50 carried the Ford WSS-M2C931-B specification for the premium Mustang engines, but that changed a few years ago. Syntec 5W-50 has been reformulated and renamed Castrol Edge Synthetic 5W-50.
Why Is Castrol Edge 5W-50 Not Suitable For Shelby Mustangs?
We spoke to Castrol and they tell us that they do not offer a 5W-50 oil option for late-model Boss 302 or Shelby Mustangs. They tell us that Edge Synthetic 5W-50 does not carry the necessary Ford specification for Mustang engines. Apparently the new Edge 5W-50 formula contains increased levels of zinc and phosphorus for classic cars with flat tappet cams (as AMSOIL does with their Z-Rod series). High levels of these additives are incompatible with modern emissions sensors and could give fits to high-tech engine gadgetry. So for late-model Boss 302 or Shelby Mustangs, Castrol is no longer in the 5W-50 engine oil sweepstakes.
Castrol Is Out, Now What?
This leaves but a hand full of 5W-50 engine oils suitable for Mustangs needing a motor oil with the Ford WSS-M2C931-B or WSS-M2C931-C spec. In our last post we announced that we are now selling AMSOIL Signature Series 5W-50 Synthetic Motor Oil for Mustangs. If you are in search for the best possible 5W-50 oil for your car, you have reached your destination. AMSOIL held nothing back in the design and quality of this full-synthetic 5W-50. It meets the applicable Ford specifications as well as the latest API SN spec.
We can have a case of this Mustang 5W-50 at your door in a day or two, regardless of where you live in Canada or the United States. Best of all, we can sell this oil at dealer cost. So to sum up, you get the best oil for your Mustang, at a price that can’t be beat. Drop us a note using the form on your right or call us at 1-800-748-5781.