Originally Posted by IMSA_Racing_Fan
I'm puzzled with the obsession towards retro-adding 0Wxx oils, especially by people with California, Arizona, etc in their profiles.
Please explain.
First and foremost, it isn't a "zero weight", it's the 0 Winter designation, which simply indicates that it passes the CCS and MRV requirements at -35C and -40C respectively to be qualified as such.
Oils blended to meet the 0W-xx winter designation typically consist of higher quality base oils to meet that qualification while still being able to properly do their job for their SAE grade, be a 20, 30, 40...etc. A good historic example was Castrol's 5w-40 versus their 0w-40. The 5w-40 had zero PAO, higher volatility and generally just worse specs, including fewer OEM approvals than the 0w-40, which was ~50% PAO.
Mobil's 0w-20 products have higher concentrations of PAO across the board versus the 5w-20 products, as yet another example.
While a 5w-20 and a 0w-20 blended the same will result in a heavier base oil blend for the 5w-20 and thus require a lower VII treat rate, they are almost never blended the same. Instead, less expensive bases are used to blend the oil with the less demanding Winter rating and so quite often the VII treat rate is the same or even higher.
Starting with European cars, the 0w-40 grade became somewhat ubiquitous in the OEM performance car scene. Carrying Porsche A40, BMW LL-01, Nissan GT-R, Mercedes AMG...etc This was later extended to domestic offerings where Mobil 1 0w-40 was the factory and service fill for all Chrysler SRT vehicles, later replaced by Pennzoil SRT 0w-40 after the FIAT merger. the 840HP Demon spec's 0w-40. GM went the same route with the Corvette, now spec'ing a 0w-40, which shouldn't surprise anyone, as they were using Mobil 1 0w-40 in their Race Program Corvettes for years. Mobil 1 0w-40 was used by numerous factory race teams from Porsche, Mercedes...etc at the 24hr races as indicated by member Doug Hillary who was quite involved with the scene, not sure if he still is.
The Euro 0w-40's have historically contained higher levels of AW additives as well, which has made them somewhat universal in their appropriateness. It was my go to oil for modified SBF's for example and I run it my Can-Am Outlander Max 1000R as well as our boats.