Originally Posted by noclutch
" Mobil 1 0W-30 is recommended by ExxonMobil for SAE 0W-30, 5W-30 and 10W-30 applications"
But is it all that? Or are they just casting a broad marketing net?
YES, it is all that. Sort of ...
The 0W designation is a winter rating, earned by an oil NOT exceeding maximum viscosity limits at standardized temperatures. For an 0W oil, these temps are - 35 *c ( - 31* F) and - 40 *c ( -40*F) as in EXTREME COLD temps. So the oil works well when cold starting in extreme winter temps.
The " 30 " is the hot ( 100*C ... 212*F ) grade. This oil has a hot viscosity of 10.9 cSt, between the 30 grade range of 9.3 and 12.4 cSt at 100*C.
So, YES, this oil is " all of that ... " . It works very well at extreme cold temps, AND falls into the 30 grade hot viscosity range. So what's not to like ?
Well, getting that 0W rating is difficult. No conventional oil can do it. And even full synthetics need some help, in the form of a thinner base oil, or more expensive base oils, and MORE pour point depressants and viscosity index improvers. These additives can break down under use, causing the oil to shear down and get thinner with use, and possibly leave deposits in the engine.
So, if you don't NEED the extreme cold temperature performance, using a 5w or 10w oil might be a better choice, as the oil will tend to be more stable in use, starting off with a thicker base oil and using less additives.
That being said, many of the 0W oils are very well built, using more of the more expensive base oils and higher quality additive packages and VII groups. Mobil 1 0W40, for example, meets some of the toughest industry standards, including Mercedes MB 229.5 and Porsche A40.