Originally Posted by Indigo
also if I am correct 15W50 is the same thing as sae 50, usally it would be written as (SAE 15W50)!
Not exactly the same... But at 212deg.F they're the same.
SAE 15w-50 means two different things. The '15w' part means it has a certain viscosity when cold, corresponding to a 15-weight "standard" oil. The '50' part means it ALSO has a certain viscosity at 212F, corresponding to a 50-wt oil.
SAE 50 just removes the requirement to match any particular viscosity when it's cold. I suppose a SAE 50 oil could be like peanut butter at 0.F & it could still technically satisfy the SAE 50 requirement.