Dont know if it is true but a guy once told me oils with high
zinc and phosphorous smell similiar to gearbox
oil. When I dumped the 15w50 mobil out it kinda stunk like gearbox
oil and it does have the 1200ppm?
zinc / phosphorous.
Anyone can get the
zinc and phosphorous they desire in any
oil by using red line break in additive and following their ratio to get the ppm you desire. I poured some in a cup with oil and the two completed disolved into each other.