OIL usage question

[Indy GT]

Howard,
I believe the reason the Ford WSS Spec was rolled from "A" to "B" is exactly for the reason the API spec was changed (I guess by API) from "SL" to the newer "SM" for spark ignition engines. Note the diesel rating structure for this oil's API rating stayed at "CF" for both.
Thus I summarize when API said automotive manufactures we now have a new higher oil specification requirement (branded as "SM" service) Ford then changed their internal WSS spec to a "B" revision to meet the new formulation compliance for the new API "SM" oil rating (which is unknown).

 

[Howard]

As I understand it, API SM requires a reduced ZDDP content to increase catalytic converter life. The reduced ZDDP, an anti-wear agent, was replaced with other anti-wear additives. Some experts believe that the replacement additives are not nearly as effective on sliding surfaces such as rocker arms as the old ZDDP. Older engines with non-roller rockers are particularly vulnerable, they say. The old 911 crowd (like me) is watching this closely. At Lime Rock's ALMS race I got to talk to Exxon/Mobil's Mobil 1 expert. He says the whole issue is nonesense, that Mobil did plenty of testing before reducing the ZDDP. Nevertheless, Mobil has come out with an "Extended Mileage" formulation for older engines, and lo and behold it has the old API SL rating. The Mobil expert says it's just marketing. Many old car owners think otherwise and are seeking out high ZDDP-content oils.

Howard

 

[BlackICE]

ZDDP more than you probably want to know.

http://www.ttalk.info/Zddp.htm

 

[Empty Pockets]

As I understand it, API SM requires a reduced ZDDP content to increase catalytic converter life. The reduced ZDDP, an anti-wear agent, was replaced with other anti-wear additives. Some experts believe that the replacement additives are not nearly as effective on sliding surfaces such as rocker arms as the old ZDDP. Older engines with non-roller rockers are particularly vulnerable, they say. The old 911 crowd (like me) is watching this closely. At Lime Rock's ALMS race I got to talk to Exxon/Mobil's Mobil 1 expert. He says the whole issue is nonesense, that Mobil did plenty of testing before reducing the ZDDP. Nevertheless, Mobil has come out with an "Extended Mileage" formulation for older engines, and lo and behold it has the old API SL rating. The Mobil expert says it's just marketing. Many old car owners think otherwise and are seeking out high ZDDP-content oils.

Howard

The above is why many people dump a little diesel engine oil into the crankcase. Evidently it still HAS the old additives.