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NE South Dakota | ZDDP requirements of a motor oil are directly proportional to valvetrain spring pressure.The trend of decreasing zinc and phosphorus is a result of observations that "modern engines" with lower spring pressures and multiple valves only require .03% ZDDP to control wear.Most older engines have significantly more pressure....current API rating is SM,and calls for .06-.08%,zn and p...new CJ-4 ratings which supersedes the CI-4 calls for no more than 0.1% p....so our diesel oils with .12-.14% will keep the wear in check.
Supplementing oil with ZDDP products should beware......having too much zn and p can reduce the effectiveness of oil detergents,the oil detergency reserve will be depleted much faster,because of changing the "balance" of additives in you oil....although CI-4 diesel oils tend to have more detergents.also too much ZDDP will foul spark plugs and 02 sensors. | |
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More bad news for older engines.
