[earossi]

After discussions with others on several Porsche forums and research into products that are on the market, I've decided that the very least that I can do is to change my selection of oils to those that still contain what appear to be the "older" adequate levels of ZDDP.

As mentioned earlier in this thread, there are Joe Gibbs oils that apparently have higher levels of ZDDP. Also, you can get ZDDP levels up in the 1300 to 1400 ppm with products from Brad Penn, Motul, and one Mobil 1 formulation, Mobil 1 V-Twin, which still runs the higher ZDDP level. My curiosity wonders why some oils can still contain the higher ZDDP levels when the US EPA mandated lower levels in order to prevent damage to catalytic converters in automobiles? I can understand why Mobil 1 V-twin would be exempt since it is meant for motorcycles, which currently are not required to use catalytic converters; but, how do Brad Penn, Motul, and Gibbs oils circumvent the regulations? Is it because they are meant for "racing" conditions which do not require the use of catalytic converters (yet)?

And, while the M1 V-Twin oil is only available in the 20W50 which works for the 911 engine, the oil does not contain friction modifiers since motorcycles normally have a common oil sump shared between the motor and the clutch. So, what impact does the lack of friction modifiers have on engine performance or longevity?