from wikipedia about zddp
EP additives, like Zinc dialkyldithiophosphate (ZDDP) additives and sulfonates, preferably calcium sulfonates, are available to consumers for additional protection under extreme-pressure conditions or in heavy duty performance situations. Calcium sulfonates additives are also added to protect motor oil from oxidative breakdown and to prevent the formation of sludge and varnish deposits. Both were the main basis of additive packages used by lubricant manufacturers up until 1990's when the need for ashless addtitives arose. Main advantage was very low price and wide availability (sulfonates were originally waste byproducts). Currently there are ashless oil lubricants without these additives, which can only fulfill the qualities of the previous generation with more expensive basestock and more expensive organic or organo....llic additive compounds. Some new oils are not formulated to provide the level of protection of previous generations to save manufacturing costs. Lately API specifications reflect that
الفكرة ان الامريكان فى سبيل الحفاظ على البيئةو اطالة عمر الكاتلتك طلعوا مواصافات قللوا فيها نسبة ال zddp و دا ما بقاش يحمى اجزاء المحركات الداخلية بنفس القوة زى زمان
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