Most of motor oils sold today are labeled as API SM standard. (Diesel oil has a different system) The SM standard was introduced around 2005 to replace the previous SL(2001) and SJ(1997) standard. The SM oils limits the ZDDP additive in the motor oil. There are two main reasons. First, the ZDDP will hurt the catalyst if the engine burns oil. Second, the ZDDP is a anti-wear additive, but it will increase the friction and reduce the fuel economy. What does ZDDP function in the engine? There are two major kinds of lubrication in the engine. Boundary layer lubrication exists where there is always metal to metal contact, like with the top piston ring, cam lobe, tappets, and rockers which makes up most of the non-corrosive wear. Hydrodynamic lubrication exists in areas like bearings, where in the best case scenario, there should never be any metal to bearing contact. In the engine, it will form a thin AW layer. The AW layer will resist the metal to metal contact in the engine.The hydrodynamic lubrication is depending on the oil viscosity and the bearing tolerance mainly. If the engine originally should use 5W20 oil. Over the time, it may need 5W30 or higher weight oil because the tolerance between the bearing and crankshaft becomes bigger. You will hear that synthetic oil will flow faster in the winter time and stay its property better at high temperature. That mainly talks about the benefit of the synthetic oil about the place where hydrodynamic lubricaton is the case. For metal to metal contact (boundary layer lubrication), the synthetical oil (group III and IV oils) will not help. The current best additive for this purpose is ZDDP. For base oil, the group V ester oil will provide better protection.
ZDDP is limited in the SM standard oil because the enviromental and energy concerns. So is there any other substitute additive? The most common used material is Moly. Moly is very slick and if made to be very tiny particles, it will float in the oil and protect the engine parts against the metal contact. However, it will corrode Copper, which is the main material used for engine bearings. And since moly is a hard metal inself, there is no ganranteed that it will bond to the surface that needs the metal-contact protection at all time.
The truth is, the SM standard oil will not protect the engine as good as the SL and SJ oils generally. If your manual says "use API SL or above", you better use a SL oil because your engine is designed for higher protection unless you can find a really good SM oil. If your manual says "use API SJ oil or above", you should never use SM oil. For even older engines, additional ZDDP additive will be necessay if SH or SJ oil can not be found.
Some oils labeled SL/SM. But I think it may not really meet SL criteria. So be carefull there.
Many people think Mobil 1 oils are the best. However, Mecedes-Benz does not recommend Mobil 1 0W30, 5W30, and 10W30 oils because they failed its high-temp/high-stress test(related to Hydrodynamic lubrication). And Nissan originally recommended Mbil 1 0W40 oil for some of its V6 engines, now recommends using Nissan ester motor oil (petroleum based) instead. Ester oil is the group 5 oil which is used as an additive to the Nissan engine oil here to provide better metal-contact protection.By the way, it is a SM oil.
If the engine is designed to use SM oil, is it OK then? The newer engines use softer valve springs and more valves per cylinder to reduce the stress on the roller cams and lifters. The pistons have Moly coatings to reduce the friction on the piston rings. But I think that proves the SM motor oil is not very protective. However, it is also not a good idea to use high ZDDP oil in these new engines either because the ZDDP will increase the friction and drag forces in the engine. The new engines did not expect this and may not run smoothly.
The conclusion: use the correct oil, based on what the manual says and the year of the engine manufactured. If you have time, money, and energy, go find the perfect oil that will last your engine longer.
ZDDP is limited in the SM standard oil because the enviromental and energy concerns. So is there any other substitute additive? The most common used material is Moly. Moly is very slick and if made to be very tiny particles, it will float in the oil and protect the engine parts against the metal contact. However, it will corrode Copper, which is the main material used for engine bearings. And since moly is a hard metal inself, there is no ganranteed that it will bond to the surface that needs the metal-contact protection at all time.
The truth is, the SM standard oil will not protect the engine as good as the SL and SJ oils generally. If your manual says "use API SL or above", you better use a SL oil because your engine is designed for higher protection unless you can find a really good SM oil. If your manual says "use API SJ oil or above", you should never use SM oil. For even older engines, additional ZDDP additive will be necessay if SH or SJ oil can not be found.
Some oils labeled SL/SM. But I think it may not really meet SL criteria. So be carefull there.
Many people think Mobil 1 oils are the best. However, Mecedes-Benz does not recommend Mobil 1 0W30, 5W30, and 10W30 oils because they failed its high-temp/high-stress test(related to Hydrodynamic lubrication). And Nissan originally recommended Mbil 1 0W40 oil for some of its V6 engines, now recommends using Nissan ester motor oil (petroleum based) instead. Ester oil is the group 5 oil which is used as an additive to the Nissan engine oil here to provide better metal-contact protection.By the way, it is a SM oil.
If the engine is designed to use SM oil, is it OK then? The newer engines use softer valve springs and more valves per cylinder to reduce the stress on the roller cams and lifters. The pistons have Moly coatings to reduce the friction on the piston rings. But I think that proves the SM motor oil is not very protective. However, it is also not a good idea to use high ZDDP oil in these new engines either because the ZDDP will increase the friction and drag forces in the engine. The new engines did not expect this and may not run smoothly.
The conclusion: use the correct oil, based on what the manual says and the year of the engine manufactured. If you have time, money, and energy, go find the perfect oil that will last your engine longer.
選擇“Disable on www.wenxuecity.com”
選擇“don't run on pages on this domain”
