# AC Delco Full Synthetic Dexos Oil vs Mobil 1



## AWR07 (Oct 23, 2018)

I know there are many very informative posts out here related to oil. Very informative, but I’ve made no conclusive headway in a situation I have. I purchased a used 2013 with only 32,000 kms (20,000 miles) on it. I’ve put 10000 kms (6,000 miles). The dealership changed the oil at purchase using AC Delco Full Synthetic Dexos. The salesman told me to change it at about 7,000 kms. His thoughts were it really was only a synthetic blend. I did change at 7,000 kms at a local spot that is owned by and Petro Canada that uses Petroleum Canada Premium full synthetic as their top premium oil. I googled it and it is dealer approved. I have put on 3,000 kms since the oil change and Ive noticed the engine has become a louder and there is a tapping sound somewhere. Quite possible I started to hear this about 2,000 km ago and it’s more noticeable now. Can’t really tell for sure but decided to start with the oil. I decided to go with a change. Couldn’t get into the dealer for a week. Figured I’d go today and decided to go with Mobil 1. Went to a different oil change location as they have an oil change package using it. I explained my situation. They checked the level and said that Cruze is known for this tapping. Didn’t really sound much different than the others they get through their location. They also mentioned they sell indentical AC Delco the dealership would have used when I picked up the car. I opted to go with that so I could have an apples to apples comparison of how the engine sounded with the original oil back in it. I’d say there is an improvement. It runs a bit quieter and the tapping seems more muted, but is still there. It still isn’t as quiet as the day I picked it up... it sounded like a new engine at that time. It was worth the cost to me to do this. I kind of hoped, didn’t really think it would completely eliminate the tapping but hoped for a better result. I figure I’ll give it 5,000 kms before the next oil change and get it to the dealer to have a look next week as I have the extended warranty. Did I make the right choice in going with the AC Delco over Mobil 1 for the reasons of the apples to apples test? Next change should I go with Mibile 1 and should I do it with sooner rather then at 5,000 kms And is this tapping really common on the 1.4? And is there a solution for it? Thanks in advance.


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## Eddy Cruze (Jan 10, 2014)

AC DELCO is the preferred oil of the CRUZE:10:


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## neile300c (Jul 8, 2014)

Dexos was a synthetic blend originally, but it changed over to full synthetic in the last year or two. All dealers use full synthetic now.


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## Robby (Mar 1, 2013)

AWR07:

I will assume you are to the Northern part of this continent (helps if you put location in at signup).

The oils: Dexos sold now is not a blend.....it is considered a full synthetic.
Per my dealer here in the USA, the current provider is Mobil.
We both believe that the current GM Dexos is Mobil 1's standard mileage synthetic oil.

A recording would help but I will speculate that the ticking you hear is likely the fuel injectors cycling. Known as 'injector click or tick' it is normal. The tick will be louder as the weather gets colder because the injector pulse width is longer (more fuel) on a cold engine.

If I am correct, any oil changing sound change is more of a mental placebo.....

But, there are engine sounds that are not injector related.....hence, the desire for a sound byte if you think it would help in your diagnostic quest.

Rob


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## AWR07 (Oct 23, 2018)

Thank to everyone for your replies. Good to know it’s a full synthetic now and the preferred oil. Yes, I am in the northern part of the continent in Oshawa, Ontario. Home of GM Canada. You could be right on the money about it it being injector related. Quite possibly it coincides with the temperature drop. We were averaging 65 - 70 up until about the second week of October. Since then it’s dropped off to 35 - 45. And even though I stated it sounded like new when I bought it there was a very faint tapping which could have just been typical injector noise. At that time we were averaging 90 degrees. I will try to figure how to get a sound bite and post it. Thanks again for all of your replies.


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## Robby (Mar 1, 2013)

AWR07 said:


> Thank to everyone for your replies. Good to know it’s a full synthetic now and the preferred oil. Yes, I am in the northern part of the continent in Oshawa, Ontario. Home of GM Canada. You could be right on the money about it it being injector related. Quite possibly it coincides with the temperature drop. We were averaging 65 - 70 up until about the second week of October. Since then it’s dropped off to 35 - 45. And even though I stated it sounded like new when I bought it there was a very faint tapping which could have just been typical injector noise. At that time we were averaging 90 degrees. I will try to figure how to get a sound bite and post it. Thanks again for all of your replies.


Or, stop by a dealer and see if they'll let you start a used, same engine Cruze.

I like to compare.

Rob


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## JFOXTON (Jul 31, 2016)

Penzoil now has a Dexos 2, 5 qt. container, for about $28 at Walmart. I use the WIX WL10021 oil filter and travel 8-10,000 miles between oil changes. I have about 170,000 miles on my diesel and just recently changed my injectors for $225ea. / AC Delco brand from a diesel supply company in South Carolina off e-bay. I kept one of the failed injectors and asked D&W Diesel to evaluate it to see if it just needed a cleaning ($35).


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## Patman (May 7, 2011)

For about $28 at Sam's/Walmart, they had 6 qts. of Mobil1 Dexos. From what I have seen at auto part stores: typically about the same for a 5 qt jug. Honestly, I don't like the 5 qt because this car takes: 4.25 qts and always have leftover in the big jug seems easier with the indiv. quart containers.


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## karmatourer (Jul 6, 2018)

Patman said:


> For about $28 at Sam's/Walmart, they had 6 qts. of Mobil1 Dexos. From what I have seen at auto part stores: typically about the same for a 5 qt jug. Honestly, I don't like the 5 qt because this car takes: 4.25 qts and always have leftover in the big jug seems easier with the indiv. quart containers.


Is it the Dexos 1.2 or Dexos 2? 
Stop killing my planet with 6 1qt. containers!:th_SmlyROFL:
The M1 Costco has is Dexos 1.2 for those who might consider it when it's on sale.And it's in your favorite containers!


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## tazzmenn (Sep 28, 2018)

I am on the left coast of the north. I am running Motul. I feel it is a better quality oil then the ac delco or mobile 1. It is more expensive but worth the piece of mind.


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## XtremeRevolution (Jan 19, 2012)

We'll start with your issue. The tapping sound, if caused by oil, would mean that you have a lot of oxidation (sludge/carbon) deposit build-up in your engine from the use of cheap/inferior oils before you bought it, or running oil out longer than it is supposed to be run. I doubt that is the case, but you can always pop the oil cap off and check the condition of the internals. More than likely, what you're hearing is either a spark plug backing out (it happens occasionally), or the EVAP purge solenoid/valve ticking, which is extremely common, and very loud. The engine is actually very quiet and would not make a sound based on what oil you're using unless you already had a serious issue with lifters being gummed up full of oxidation deposits. Again, I doubt this is the case. 

Now, on the topic of oil, do not be fooled by "full synthetic." That is absolutely meaningless. It is just another way for the big oil companies to continue selling you their cheapest products while making it look like they're selling you something great. Down here we can sometimes get Mobil 1 and Pennzoil Platinum for $17-$18 on rebate for a 5-quart jug. Those are not 100% synthetic prices. There's a difference between "full synthetic" and "100% synthetic" as Motul and AMSOIL can explain below: 
https://www.motuloil.com.au/2016/12/26/81/
https://blog.amsoil.com/how-much-synthetic-is-in-my-oil/

A recent Lubes n Greases magazine article was also written on this topic: 
2017_11 - November 2017 - LNG

These manufacturers can call an oil "full synthetic" as long as they are using a synthetic base oil, but it doesn't have to be all of the base oil blend, just the primary, and the quality of base oils even within API groups (group 3, group 4, etc.) varies wildly. A manufacturer can use a cheap group 3 base oil, blend it in with, say, 25-35% group 2 conventional as an additive carrier (additives generally don't bond well to synthetic base oils), and call the whole package "full synthetic" even though only 65-75% of the oil is actually synthetic, and even then, that's a cheap group 3, not even a high end group 3 or a group 5 ester/PAO blend like what AMSOIL makes. 

Motul does make 100% synthetic base oils, with a good quality group 3 in their 8100 series as far as I can tell. Solid products.

I personally don't think there is a major difference between what GM sells and Mobil 1's vanilla or "extended protection" products.


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## rally (Jun 17, 2017)

*jackleg*

You can try the old trick with a long screwdriver or purchase a mechanic stethoscope and listen to different parts of the engine. Let the engine warm up and use scope or put screwdriver to your ear and touch the injectors with the tip. Lots of times you can locate the sound.


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