Group III
Similar characteristics to Group II base stocks, Group III base stocks have higher viscosity indexes.
Some Group III
base stocks with VHVI are sometimes referred to as Group III+. Group III base stocks are produced by a wide range of
processes, such as further hydrocracking of Group II base stocks, or by chemically modifying slack wax, which is the
end-product of the dewaxing process, which improves the VI.
Some Group III+ oils are created by highly processing oil
into what have been called “Severely Hydrocracked,” “Chemically Modifed,” or “Semi-Synthetic.” Castrol™ Syntec® and
Valvoline™ Durablend® are oils manufactured from Group III base stocks
و هنا بيوضح ان زيت كاسترول Syntec كان يصنع من زيوت المجموعه الرابعه غير معدنى PAO .. يحتوى على 70% زيت مجموعه رابعه غير معدنى PAO و الباقى زيت اساس أخر
ثم قامت كاسترول بتغيير التركيبه بتاعت Syntec الى مجموعه 3+ معدنى بالكامل
In 1999 the Mobil™ Oil Corp. lodged a complaint against
Castrol™/Shell™ with the NAD (National Advertising Division of the Council of Better Business Bureaus). Mobil’s™
claims were that
Castrol™ had changed the formulation of its “Syntec®” PCEO from a
nearly 70% PAO Group IV base
to
100% mineral oil Group III+ base, and yet still misleadingly advertised the oil as synthetic. (
Mobil™ itself had been
marketing VHVI Group III based oils in Europe at that time and had advertised them as synthetic.)11 It also charged that
Castrol™ had changed Syntec® to a “degraded” product to the detriment of the consumer, yet was advertising the oil as
“superior” to all other motor oils, both synthetic and conventional.
خلاصه الكلام ده ايه
- تركيب الزيوت مجهول تماما للمستخدم
- التركيب قد يتغير فى اى وقت
- يمكن خلط المجموعات مع بعض مثلا مجموعه رابعه مع مجموعه ثالثه او ثانيه مثلا
- المجموعه 3+ بتكون زيوت VHVI ( مؤشر لزوجه مرتفع جدا )عاده تنتج من معالجه الشمع WAX بالاضافه الى انتاجها بطرق اخرى .. و هى زبوت مرتفعه الاداء
- زيوت المجموعه الرابعه ايضا تنتج عاده من معالجه ال WAX ثم تستكمل مراحل تصنيعها بالاضافه الى انتاجها بطرق اخرى
يعنى كله تخمين .. الا اذا اعلنت شركه صراحه و بوضوح عن تركيب زيوتها