Use of synthetic oil
04-06-2014, 09:28 PM
#21
if anyone cares for a quick history lesson, which may or may not be entirely accurate but the way i understand it:
the myth or belief that once you run synthetic oil you cannot go back does have some merit but you need to understand why. and a lot of beliefs and thought processes are like this today and is a result of ignorant people not knowing any better and republishing what is already on paper not knowing how things currently work or what changed...
way back prior to the 1980's i believe automotive synthetic engine oil and possibly mobil-1 was made up of PAG oil. PAG oil is not compatible with conventional petroleum based oils, which then resulted in the fact if you used PAG synthetic oil in your car engine you needed to keep using it and thus "couldn't switch back to conventional".
now... if you have some common sense you would realize that with anything mechanical you can do anything you want if you do things right meaning you could switch back and forth with any oil provided you flushed your engine properly of whatever oil prior to changing to some other oil that was incompatible with the previous. In industry this is not that big a deal considering if the change in oil reaps economic benefits and longer equipment life, but for the regular person owning a car it would be borderline ridiculous to flush the engine crankcase in terms of cost and effort. and the people selling you stuff in the automotive market really don't care about how hard things are for you they will just market their product with whatever lies they can to get you to buy it and certainly not tell you the cons and problems down the road you may face. This may also have been before API and the big push for automotive engine oils to meet certain requirements. since at least the 1990's the federal gov't including the epa have leaned on the automotive industry to produce cars with better fuel economy and less emissions resulting in engine oils going from API SJ to currently SN and going from no viscosity recommendation to 5w-30 and currently 5w-20 and 0w-20 oils are common.
the viscosity of the oil has most to do with fuel economy, not emissions, and viscosity is largely independent of API classifications. But the API going from SJ to SN classification falls on the emissions side of things, they have continually been reducing and restricting additives in the oil which are detrimental to emissions, most of which is phosphorus because when oil gets burned that phosphorus gets into the exhaust and poisons the catalysts in the catalytic converter.
flip to now, any automotive engine oil sold in the US having an API certification will be compatible with all other oils having any API certification. To my knowledge no one is marketing an engine oil that has PAG as a base oil, they are all petroleum based. The synthetic part refers to what is known as group III base oils which are conventional petroleum based, group IV oils with are PAO which are considered true synthetic, and group V oils which are ester-based and also true "synthetic". it's all compatible, and in fact your cheap conventional oil does probably have some PAO in it to get the oil's additive package to be in the oil. and many synthetics on store shelves if they do have PAO is not 100% PAO it too has some conventional petroleum based oil in it in order to get the additive package to mix and stay suspended in the oil. and hopefully "synthetic blend" oils would have caused a light bulb to go off in your head before i typed all this.
here's an article if interested http://www.machinerylubrication.com/...-synthetic-oil
you choose oil viscosity based on operating temperatures that the oil needs to work at. your owner's manual stating use 5w-30 is largely a result of epa requirements for fuel economy and based for north america U.S. and getting you through the 3yr/36k mile warranty. if you run your engine hard in hot 100° + weather on 5w30 and engine oil gets over 250° routinely, the oil will thin too much and not protect along with oxidize and you will have engine failure sooner than if you used a 40wt or 50wt oil. this is especially true when idling an engine less than 800 rpm on low viscosity hot oil, the oil pump outputs less which results in oil pressure down to 20psi and lower. true synthetic oils offer better oxidation stability at high temperatures above 250° and flow better at extreme cold temperatures less than -10°F for starters. if you don't fall outside that -10° F to 250°F a synthetic isn't doing much for you other than waste your money compared to choosing the correct viscosity in today's API SL, SM, SN conventional engine oil. Also know there is no legal definition of automotive synthetic engine oil and history has proven that, the oil companies can market however they wish.
the myth or belief that once you run synthetic oil you cannot go back does have some merit but you need to understand why. and a lot of beliefs and thought processes are like this today and is a result of ignorant people not knowing any better and republishing what is already on paper not knowing how things currently work or what changed...
way back prior to the 1980's i believe automotive synthetic engine oil and possibly mobil-1 was made up of PAG oil. PAG oil is not compatible with conventional petroleum based oils, which then resulted in the fact if you used PAG synthetic oil in your car engine you needed to keep using it and thus "couldn't switch back to conventional".
now... if you have some common sense you would realize that with anything mechanical you can do anything you want if you do things right meaning you could switch back and forth with any oil provided you flushed your engine properly of whatever oil prior to changing to some other oil that was incompatible with the previous. In industry this is not that big a deal considering if the change in oil reaps economic benefits and longer equipment life, but for the regular person owning a car it would be borderline ridiculous to flush the engine crankcase in terms of cost and effort. and the people selling you stuff in the automotive market really don't care about how hard things are for you they will just market their product with whatever lies they can to get you to buy it and certainly not tell you the cons and problems down the road you may face. This may also have been before API and the big push for automotive engine oils to meet certain requirements. since at least the 1990's the federal gov't including the epa have leaned on the automotive industry to produce cars with better fuel economy and less emissions resulting in engine oils going from API SJ to currently SN and going from no viscosity recommendation to 5w-30 and currently 5w-20 and 0w-20 oils are common.
the viscosity of the oil has most to do with fuel economy, not emissions, and viscosity is largely independent of API classifications. But the API going from SJ to SN classification falls on the emissions side of things, they have continually been reducing and restricting additives in the oil which are detrimental to emissions, most of which is phosphorus because when oil gets burned that phosphorus gets into the exhaust and poisons the catalysts in the catalytic converter.
flip to now, any automotive engine oil sold in the US having an API certification will be compatible with all other oils having any API certification. To my knowledge no one is marketing an engine oil that has PAG as a base oil, they are all petroleum based. The synthetic part refers to what is known as group III base oils which are conventional petroleum based, group IV oils with are PAO which are considered true synthetic, and group V oils which are ester-based and also true "synthetic". it's all compatible, and in fact your cheap conventional oil does probably have some PAO in it to get the oil's additive package to be in the oil. and many synthetics on store shelves if they do have PAO is not 100% PAO it too has some conventional petroleum based oil in it in order to get the additive package to mix and stay suspended in the oil. and hopefully "synthetic blend" oils would have caused a light bulb to go off in your head before i typed all this.
here's an article if interested http://www.machinerylubrication.com/...-synthetic-oil
you choose oil viscosity based on operating temperatures that the oil needs to work at. your owner's manual stating use 5w-30 is largely a result of epa requirements for fuel economy and based for north america U.S. and getting you through the 3yr/36k mile warranty. if you run your engine hard in hot 100° + weather on 5w30 and engine oil gets over 250° routinely, the oil will thin too much and not protect along with oxidize and you will have engine failure sooner than if you used a 40wt or 50wt oil. this is especially true when idling an engine less than 800 rpm on low viscosity hot oil, the oil pump outputs less which results in oil pressure down to 20psi and lower. true synthetic oils offer better oxidation stability at high temperatures above 250° and flow better at extreme cold temperatures less than -10°F for starters. if you don't fall outside that -10° F to 250°F a synthetic isn't doing much for you other than waste your money compared to choosing the correct viscosity in today's API SL, SM, SN conventional engine oil. Also know there is no legal definition of automotive synthetic engine oil and history has proven that, the oil companies can market however they wish.
04-07-2014, 01:53 AM
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But the API going from SJ to SN classification falls on the emissions side of things, they have continually been reducing and restricting additives in the oil which are detrimental to emissions, most of which is phosphorus because when oil gets burned that phosphorus gets into the exhaust and poisons the catalysts in the catalytic converter.
For example, Valvoline VR1 (common oil that those of us with flat tappet engines use for the higher ZDDP content required in such an application) states on the bottle "Exceeds engine protection requirements for API Services SN/SM/SL", yet the oil contains .13% zinc and .12% phosphorus - well in excess of the limits for SN/SM oils that have an ILSAC rating of GF-3/4/5. This is possible because VR1 does not have any ILSAC rating. So if you are looking at specialty oils that do not contain an ILSAC rating, you may in fact see API Service ratings of SM or higher even though the ZDDP content is well beyond that of "normal" ILSAC rated, API SM+ oils with GF-3+ rating.
Last edited by RPM WS6; 04-07-2014 at 02:00 AM.
04-08-2014, 11:39 AM
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04-08-2014, 03:55 PM
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Why are people switching the weights of their oil? I thought you were supposed to only run the weight recommended by the factory due to clearance issues. The engine "calls" for a specific weight due to clearances or something like that.
04-08-2014, 05:45 PM
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- Aftermarket builds might have different clearances that require a different weight.
- The engine may be operated in a climate where the factory recommeded weights are not ideal.
- UOAs have shown that [even stock internal] LS1s typically respond well to oils that are on the thick side of a 30 weight or the thin side of a 40 weight. This is why I prefer M1 0w40 for my LS1s, since it tends to run on the thin side of a 40.
- The engine may be operated in a climate where the factory recommeded weights are not ideal.
- UOAs have shown that [even stock internal] LS1s typically respond well to oils that are on the thick side of a 30 weight or the thin side of a 40 weight. This is why I prefer M1 0w40 for my LS1s, since it tends to run on the thin side of a 40.
