Armed Polite Society
Main Forums => The Roundtable => Topic started by: Fly320s on November 14, 2011, 03:56:49 PM
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I'm getting some work done on my car today after I discovered last night that one of my shocks died. Another customer is here for an oil change on his new Chevy Malibu. The tech comes in with the oil filler cap in his hand and says that Chevy requires only Mobil 1 be used. I didn't think a "normal" engine would require a synthetic oil. Is this like requiring premium gas?
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synthetic oil is an excellent product, but i didn't know that car manufacturers were requiring it.
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IIRC, one of the Corvette models required synthetic.
Chris
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IIRC, one of the Corvette models required synthetic.
Chris
Requiring special oil for high performance engines makes sense, but the Malibu is a sedate sedan.
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Didn't know anybody "required" it, but some engines use as light as 0-20W oil and I think that is only available in Syn.
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Requiring special oil for high performance engines makes sense, but the Malibu is a sedate sedan.
Says you! :P :P :P
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Requiring special oil for high performance engines makes sense, but the Malibu is a sedate sedan.
It was, at the time, a pretty simple engine for a high performance car. The Malibu likely has a more advanced engine with even tighter tolerances (this being at least 10 years later).
Chris
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Since about 2002-04 ish, it's become much more common to see OEM requirements for wither synthetic or a synthetic blend. Tolerances have gotten much tighter then they used to be and good, thin oil is the only way to make it through the warranty period.
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There is no requirement for synthetic oil, the recommended oil is Dexosâ„¢ lisenced. It's not an oil industry or SAE standard. Not many have paid the royalties to use the Dexosâ„¢ logo.
Is is better? I don't know what their standards are. Is is a money making scheme? Yep. http://gmdexos.com/
This reminds me of the Dexcool antifreeze 15 years ago that turned to sludge before they changed the formula.
Not all oils labeled synthetic really are. The standard motor oils are Group 2, you can get them at Mal-Wart for less than $20 per gallon. Most synthetic oils are actually group 3, and really they are just the good batches of group 2 oils when the refinery has a good day, and the additive packages are usually better. Group 4 is PAO, and they are the synthetic oils. Mobil 1, AMSoil, etc. fall into this category. They have a much wider temperature range and are useful in the arctic and turbocharged vehicles. They also last longer before breaking down, but that's a double edged sword. No engine is perfect, you will have blowby fuel dilluting the oil over time, I'd rather use the cheaper stuff and change it more often.
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Rotella T6 synthetic. Good,. and also cheap.
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Rotella T6 synthetic. Good,. and also cheap.
That's great oil if you need a 5w40 weight oil. Not so good if you need 0w20 or 20w50.
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Not all oils labeled synthetic really are. The standard motor oils are Group 2, you can get them at Mal-Wart for less than $20 per gallon. Most synthetic oils are actually group 3, and really they are just the good batches of group 2 oils when the refinery has a good day, and the additive packages are usually better. Group 4 is PAO, and they are the synthetic oils. Mobil 1, AMSoil, etc. fall into this category.
It all depends -- on your definition of "synthetic."
Several years ago, Mobil sued a number of the other makers of "synthetic" motor oils, claiming that Mobil-1 was synthetic and the others were only synthetically-modified petroleum oils. Mobil lost. The data showed that, regardless of how they got there, the final products were essentially and effectively the same.
Soon after getting their posteriors handed to them in court, Mobil announced that Mobil-1 had been reformulated. That was when the containers first started using the term "Tri-Synth" (or something with "Tri-" in it). Which means Mobil threw in the towel and started making Mobil-1 the same way the other guys make theirs.
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An Amsoil rep promised my uncle that if he went with their oil he would be fine going 25,000 miles on a change, and also said that if he used their oil and their special filter, he would never have to change his oil again as long as he had the truck (2005 Chevy Silverado 2500 Turbo Diesel), AND they would guarantee it against oil-related damage. This special filter is apparently some $$$ up front and has to be installed because it is not just a filter but some tubing and such. They called it a bypass filter. Apparently they don't sell too many because people don't want to fork out the $$$ up front.
Interesting claim to make, and it certainly turns the general knowledge of oil changing on its head.
Now that I am reminded of it I did some quick googling: http://www.tsadvancedsynthetics.com/facts/AMSOIL_By-Pass_Oil_Filter_System.htm
Apparently one guy went 400,000+ miles on a diesel and never changed the oil with this system. Engine was torn down and found almost no wear. :O
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IIRC, I also recall some aftermarket oil filter that was essentially a giant roll of paper. Although tougher and thinner than what would be on your usual roll of paper towels or TP.
All you had to do was top off oil losses, and never change anything but the paper roll. It worked because it had several thousand times the surface area of a regular filter.
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Soon after getting their posteriors handed to them in court, Mobil announced that Mobil-1 had been reformulated. That was when the containers first started using the term "Tri-Synth" (or something with "Tri-" in it). Which means Mobil threw in the towel and started making Mobil-1 the same way the other guys make theirs.
The difference is a group III (dino-juice) base stock with a synthetic additive package or a group IV or V (full syth) base stock. The full synth products do have a slight edge if measure to the Nth degree, but for the real world a blend works for us mere mortals. Mobil got their knickers in a knot because Castrol was using a group III base stock with a synth additive package and calling it "synthetic".
As for oil change intervals... the 3/36 recommended OCI is a holdover from the bald old days when motor oil was almost an afterthought. It was some brown greasy stuff that was liquid enough to pour into a bottle. Now, even cheapo oils that meet an auto mfg's spec will go way beyond a 3/36 OCI without any appreciable loss in critical performance. Go to BobIsTheOilGuy.com and visit the forums. There are folks there who take stretching oil usuability to the max and are using oil analysis to determine when their oil is actually in need of changing. With nothing more than regular filter changes and top offs some are seeing up to 15k on regular (group III) base stock oils and upwards of 25-30k on group IV and V synthetics.
Brad
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What about us low-mileage drivers? I average about 6,800 miles per year and I've been doing my oil changes every 6 months, regardless of mileage. Are the modern oils good for this type of driving?
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What about us low-mileage drivers? I average about 6,800 miles per year and I've been doing my oil changes every 6 months, regardless of mileage. Are the modern oils good for this type of driving?
You will do fine that way.
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Depends on how you put that 6800 miles on. If it's a couple of longer runs where the engine gets to full operating temp for at least 20-30 minutes then you're fine with running the oil a bit longer. That's enough heat and time to evaporate away the condensation that can form inside your crankcase. If you do a bunch of short hops that never really let the car get up to operating temp then you can have problems with condensation breaking down the oil ("chocolate milk" oil). That's more of an issue and you would definitely need to change your oil more often in those conditions.
I would think a 6 month OCI would be stretching it for a short-hopper, but not egregiously so given the quality of modern motor oils (especially the better synthetics like Mobil 1).
Brad
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An Amsoil rep promised my uncle that if he went with their oil he would be fine going 25,000 miles on a change, and also said that if he used their oil and their special filter, he would never have to change his oil again as long as he had the truck (2005 Chevy Silverado 2500 Turbo Diesel), AND they would guarantee it against oil-related damage. This special filter is apparently some $$$ up front and has to be installed because it is not just a filter but some tubing and such. They called it a bypass filter. Apparently they don't sell too many because people don't want to fork out the $$$ up front.
Interesting claim to make, and it certainly turns the general knowledge of oil changing on its head.
Now that I am reminded of it I did some quick googling: http://www.tsadvancedsynthetics.com/facts/AMSOIL_By-Pass_Oil_Filter_System.htm
Apparently one guy went 400,000+ miles on a diesel and never changed the oil with this system. Engine was torn down and found almost no wear. :O
Dude sith th ed diesel and the Amsol rep are both fulla *expletive deleted*it
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Dude sith th ed diesel and the Amsol rep are both fulla *expletive deleted*
I believe it after looking into it more.
The filter they are talking about is a bypass filter, which means it only receives about 5-10% of the output of the oil pump. There is still a standard full-flow filter on the engine which receives 100% of the output of the pump, but then a small portion of that is diverted through the bypass filter and then returned back to the system. A full-flow filter traps particles as small as about 20 microns, whereas the bypass system can trap sub-micron particles. The extreme filtration probably explains why it only handles a portion of the oil coming through. I imagine that you COULD build a sub-micron filter that could handle full-flow volume, but it would be enormous.
The reason that it works is that full synthetic oils simply do not break down over time, but eventually need to be changed because they get so dirty with the tiny particles which a full-flow filter can't remove. If you have a sub-micron filter keeping your full synthetic oil clean, then you can run that same oil indefinitely.
Using the system, you still need to have your full-flow filter changed periodically, and I think they recommend 25,000 miles, and the oil needs to be topped off at that point from losing what is in the filter, and any other losses.
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I believe it after looking into it more.
The filter they are talking about is a bypass filter, which means it only receives about 5-10% of the output of the oil pump. There is still a standard full-flow filter on the engine which receives 100% of the output of the pump, but then a small portion of that is diverted through the bypass filter and then returned back to the system. A full-flow filter traps particles as small as about 20 microns, whereas the bypass system can trap sub-micron particles. The extreme filtration probably explains why it only handles a portion of the oil coming through. I imagine that you COULD build a sub-micron filter that could handle full-flow volume, but it would be enormous.
The reason that it works is that full synthetic oils simply do not break down over time, but eventually need to be changed because they get so dirty with the tiny particles which a full-flow filter can't remove. If you have a sub-micron filter keeping your full synthetic oil clean, then you can run that same oil indefinitely.
Using the system, you still need to have your full-flow filter changed periodically, and I think they recommend 25,000 miles, and the oil needs to be topped off at that point from losing what is in the filter, and any other losses.
That filter still doesn't address the problem of fuel dilution from blow-by. Most if it goes back through the PCV valve and gets burned again, but not all of it. The cheapest way to remove that fuel from the oil is to change it. Less than 2% fuel is considered normal at an oil change, more than that and oil viscosity becomes a problem.
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Reminds me of the stuff I have heard about Royall Purple additive.
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That Malibu engine is very high tech. 4 and 6 CHL both have a dual overhead cam system with variable timing. The actuators that control the cams are very oil maintenance sensitive. Standard oil at 5k miles will clog the screens and turn on the check engine light. This new system requires the synthetic blend called dexos to meet the oil change intervals of 7500 miles.