0W-40 - Castrol vs Mobil vs Pennzoil

[spiderbypass]

Also from looking at Castrol MSDS again I would venture it is made up of 25-50 PAO and 25-50 GTL as there are many GTL CAS numbers towards the bottom of the page with less than 10 percent heavy parafinic distillates which likely help the additive package solubility as PAO and GTL are not the best with additive solubility.

 

[nielkfj]

I don't know if this adds anything to the conversation, but the Castrol Edge Professional 0W-40 MSDS also shows only 25-50% PAO.

https://msdspds.castrol.com/ussds/amersdsf.nsf/Files/6CF28F63D232748D80258178003A069E/$File/11260899.pdf

For some reason "US" is stated in the product code, rather than BE or DE. It also has the same date as the BE MSDS.

Presumably the "Professional" would the superior version, so perhaps we can trust a 25-50% PAO formulation.