Originally Posted by TrackRat
If Mobil had submitted the Turbo Diesel oil and passed the LL-01 oil test sequence you can be certain they would advertise this.
I really doubt they would break the market segmentation to make a redundant product.
0w40 is niche (usually in very small stock)
5w40 is mainstream (jugs of it abound everywhere)
If they both had ll-01 approval, people would just buy the cheaper one - or 5w40 would both have to be more expensive (+endorsement), or they would have to introduce a 3rd product to take the price point of the 5w40.
Here are some interesting links that I found :
0w40 has 0.10 phosphorous (units not stated)
5w40 has 0.12 phosphorous (units not stated)
The question of phosphorus and zinc.
Phosphorus (a component of ZDDP - Zinc Dialkyl-Dithio-Phosphate) is the key component for valve train protection in an engine and 1600ppm (parts per million) used to be the standard for phosphorus in engine oil. In 1996 the EPA forced that to be dropped to 800ppm and then more recently (2004?) to 400ppm - a quarter of the original spec. Valvetrains and their components are not especially cheap to replace and this drop in phosphorus content has been a problem for many engines (especially those with flat-tappet type cams). So why was the level dropped? Money. Next to lead, it's the second most destructive substance to shove through a catalytic converter. The US government mandated a 150,000 mile liftime on catalytic converters and the quickest way to do that was to drop phosphorous levels and bugger the valvetrain problem. Literally.
In the US, Mobil 1 originally came out with the 0W40 as a 'European Formula' as it was always above 1000 ppm. This initially got them out of the 1996 800ppm jam and knowledgeable consumers sought it out for obvious reasons. Their 15W50 has also maintained a very high level of phosphorus and all of the extended life Mobil synthetics now have at least 1000ppm. How do they get away with this? They're not classified as energy/fuel conserving oils and thus do not interfere with the precious government CAFE (corporate average fuel economy) ratings. (See my section on the EPA and fuel economy in the Fuel and Engine Bible for more info on this). This also means that they don't get the coveted ratings of other oils but they do protect your valvetrain. The same rule of thumb is true for racing oils like Royal Purple - because they're not classified as energy / fuel conserving, it would seem they still contain good quantities of ZDDP.
You say the new Mobil 1 Racing oils are not for street use. Why is that? Does that mean I can't use these oils if my race car is also my daily driver?
Automotive street use oils that meet the latest industry standards are required to have a lower level of Zinc and Phosphorus anti-wear chemistries than oils formulated years ago. The latest automotive street use engine oils are designed to be compatible with emission control equipment. Mobil 1 Racing oils are formulated with anti-wear (Zinc/Phosphorus) chemistries at twice the level of automotive street oils to provide enhanced protection of highly loaded valve train systems found in some race engines. Based on the high level of anti-wear chemistries, Mobil 1 Racing oils are not recommended for street use.