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Hi y’all,
I have a 2015 Malibu with the 2.5L motor, and since day one I have used synthetic blend in it. Recently, when I go in to these quick lube shops, they refuse to put anything in it but full synthetic For “liability purposes”. Am I doing this wrong? Will using only synthetic blend really make a difference at this point? I am way past warranty and after 105k everything is still in tip top shape.
 

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GM switched to second generation Dexos 1 standards, which is full synthetic. That's why the quick lube shops are weary of using anything else, and it's what you should use as well.

I'm actually impressed your quick lube shops are so discerning. Many of them will pour whatever trash conventional oil they have on hand, slap on a 2 dollar Fram filter and send you on your way.
 

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Discussion Starter #3
GM switched to second generation Dexos 1 standards, which is full synthetic. That's why the quick lube shops are weary of using anything else, and it's what you should use as well.

I'm actually impressed your quick lube shops are so discerning. Many of them will pour whatever trash conventional oil they have on hand, slap on a 2 dollar Fram filter and send you on your way.
Most don’t care, but Midas does. My concern is should I make that transition or keep up with the synthetic blend? I have always used Valvoline Max Life which says it is dexos approved.
 

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Your always better off with full synth. . Semi is just that, there is no standard for semi. We assume it's 50/50 but that's not true as it can be only 10% or whatever. You'll never see exactly how much synth. is in the bottle on the bottle no mater what the brand.
 

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I always felt synthetic blend was the worst of both worlds...and like repairman54 has stated; what is the ratio of synthetic to dino oil?...

watch for sales and rebates and you can find full synthetic oils for cheaper than you can buy blends and if you go to a GM dealership (any of them) following the latest Dexos 1 Generation 2 protocol you will get full synthetic oil with your change...

Good luck with your choice

Bill
 

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possibly the reason for the quick change place using full synthetic for liability purposes is that your engine calls for Dexos 1 Generation 2 oil which currently is a full synthetic oil (as mentioned by cp-the-nerd)...

you may put whatever you like in your car but many times when someone else is doing the oil change, they follow the manufacturers specification...

Good luck with your choice

Bill
 

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Full synthetic since I got her at 40k mobil 1 oil and filter have settled as my go to! I have tried different oils like valvoline and penzoil. In all honesty it could just be the car but she burns oil with the other brands barely any oil is lost with Mobil 1
 

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After the 2016 Malibu Limited was purchased new, I switched out the oil/filter at roughly 500 miles to be full synthetic Quaker State. Ever since then, it was that full synth oil and I noticed that the RPM gauge was roughly 450 (a little bit under the gauge's mark) at idle each time. Recently, I tried the chevy dealerships full synth oil/filter change to that ACDelco full synth oil. The RPMs at idle are now typically at 600 RPM (a little bit above the gauge's mark). I assume that the computer is feeding just enough fuel so that the engine doesn't stall out. Does this higher idle imply that the ACDelco oil has more overall resistance, thus the idle speed must be higher to prevent stall? At the next oil change, I'll go back to full synth QS, and if the idle RPM drops back to 450, then what can I infer from this other than different brands of oil have different performance?
 

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If it's dropping to 450, wouldn't that mean that for the same amount of fuel, the QS is thicker and slows the crank just a bit more?

Or possibly the fill level is different when you do it vs. when someone else does it?

No matter what you find out, stick with a good brand of full synthetic and you can't go wrong.
 

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DD...that's what I would think as well...the QS full synthetic has more resistance and the dealership oil (probably a Mobil Oil product) has less resistance when at idle...but oils of the same weight really should not effect idle speed that much...

Bill
 

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Idling at 450 rpm is bizarrely low. Is Quaker State synthetic approved by the dexos certification? I've always been told that Quaker State is one of the lowest quality big oil brands so I've never touched it.
 

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Idling at 450 rpm is bizarrely low. Is Quaker State synthetic approved by the dexos certification?
The 5 quart jugs are marked Dexos 1 (not 2) when I had last used QS. The chevrolet dealer I got my full synthetic oil change at is Good Chevrolet. I paid for the full synthetic ACdelco Dexos 2, but the invoice was marked as having conventional oil. The service representative said it was actually full synthetic dexos2 and I should not worry about it. They only marked it conventional because their database program didn't have enough slots for the dexos2 oil. Was I lied to? I can't really tell by looking at oil on the dipstick if it is synthetic or not. Well, the new oil is 600 RPM and QS was 450 RPM.
I wonder how many people out there have tried looking at their RPM before and after oil changes to a different oil. I know lots of people say oil is oil, but if the RPMs are different, at the very least one can say the engine seems to notice something is different.

As for why I picked QS Ultimate Durability full synth, it was after reading through test results at the 540RAT Oil Database. QS full synth is quite highly rated there, but of course oil formulations change year after year. Mr Rat does update the test results every so often, but there are just many different oils to test.

540RAT Oil Database: 540 RAT - Tech Facts, NOT Myths
 

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The marking of oil change service records as "conventional" is common at dealers. They apply a labor job and quick mishit. The advisers try and explain as it not fitting but they have the right description they just marked the wrong thing. It's unprofessional - you shouldn't have to wonder if they used up some four year old conventional on your car. The lube techs can be bad but they aren't that bad.

My favorite sentence in the "540rat" blog is "My advice is, ignore any critics of my Blog, because they have always been wrong, and cannot be trusted." That coming from a nameless author claiming qualifications no one can verify that uses RANDOM capital LETTERS on his blog to emphasize SHOUTING at YOU. I find the information interesting but the tone of that blog almost unreadable.
 

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If the oil that caused it to drop to 450 RPM is available, for $28 you can have it tested. If it comes back as conventional, you could have a case of fraud. Seek a lawyer for more advice if you want it.
 

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Dexos 2 is (mostly) a diesel oil isn't it???...does your motor call for Dexos 1 Generation 2 or Dexos 2???...could that be causing the issue you are seeing??...

Bill
 

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okay...disregard my last post in as much as you weren't using Dexos 2 but just writing it (I suspect)...I believe the motor oil put in your car at the dealership was the proper oil for your car...

what motor oil weight are you buying when you do the oil changes and what weight is the dealership putting in???...are they the same weight???...

Bill
 

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Dexos 2 is (mostly) a diesel oil isn't it???...does your motor call for Dexos 1 Generation 2 or Dexos 2???...could that be causing the issue you are seeing??...
Sorry for the confusion on dexos generation notation. It was QS 5w20 SN Full Synth Dexos 1 Generation 1 that had 450rpm fairly consistently year after year of changes. When I switched to ACDelco 5w20 SNplus Full Synth Dexos 1 Generation 2 (as told by service advisor despite invoice marked as conventional oil), the RPMs moved up to approx 600rpm.
 

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that does seem very strange that two motor oils of the same viscosity rating should have such varied RPMs shown on your tachometer...450 seems low and 600 seems more like it should be...I'm also surprised that you can still find an oil that is Dexos 1 Generation 1 still in locations as it hasn't been the recommended GM oil for a few years now...

good luck with your car

Bill
 
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