Pennzoil's regular multigrade 5W30 gives a borderline pumping temperature of -35C. However, since the Mobil 1 site didn't state the borderline pumping temperature for Mobil 1 5W30, I sent them an email asking for it. Their reply was that Mobil 1 was tested to the SAE J300 Standard and "Mobil 1 5W30 complies with both maximum yield stress and apparent viscosity requirements, that is, there is 0 yield stress and the viscosity is less than 60,000 cp@-35C".
Does the Mobil 1 reply mean that the Borderline Pumping Temperature is - 35C, i.e. the same as Pennzoil's petroleum multigrade?
Borderline pumping temperature is measured at -35C for all 5w oils, regardless whether they are synthetic or not. 10w oils are measured at -30. I believe the 60,000 cp Mobil told you is the maximum viscosity allowed for an oil to be included in the particular "w" category. So a 5w must be 60,000 or less at -35C, a 10w 60,000 or less at -30C. See the third column of this chart: http://www.infineum.com/information/viscosity.html
Since Mobil does give pour point, I suggest you compare the two oils on that parameter. However, the best cold flow property is the MRV (Mini Rotary Viscometer) test, so I have heard.
This message has been edited. Last edited by: TallPaul,
