Switching to Synthetic

[phatcatz]

OK - so I got myself a 2010 Silverado with GM's Oil Life Monitor. I have always changed the oil at the dealership according to the OLM with conventional 5W-30 oil.

So this summer my wife got a 2015 Equinox that specifies Dexos oil. Well not the type to spend a whole lot of time thinking about service intervals, I got to wondering about this Dexos specification. Well it turns out that GM went to this because, due to Variable Valve Timing, the engine oil actually does the work in moving the cam to different positions.

Well, I got to thinking MY truck has VVT and from 2011 and up Siverados were spec'd for Dexos oil for this reason.

Sadly my truck was left out.

So my question is this: do vehicles that have the Dexos specification have a different OLM algorithm than the algorithm used in conventional oil trucks?

and if they do, can I re-flash my OLM so that it reflects the fact that I am using a upgraded oil?

 

[Blinker]

Dexos came about more because of turbo charged engines (2011 chevy cruze) than because of VVT. VVT runs fine on non dexos oil, your truck has the same OLM calibration as the 2010. The GM 3.6 DI and 2.4 DI motors up to a certain year model had a recall to recalibrate the OLM.

 

[Blinker]

And believe it or not for those two engines that were recalibrated GM shortened the OCI too, and thats with dexos oil. Your engine does not have these issues so you are good to go.

 

[phatcatz]

Originally Posted By: stower17
Dexos came about more because of turbo charged engines (2011 chevy cruze) than because of VVT. VVT runs fine on non dexos oil, your truck has the same OLM calibration as the 2010. The GM 3.6 DI and 2.4 DI motors up to a certain year model had a recall to recalibrate the OLM.


5 min on Google =

http://gmauthority.com/blog/gm/chevrolet/cruze/chevrolet-cruze-sales-numbers/
http://gmauthority.com/blog/gm/chevrolet/silverado/chevrolet-silverado-sales-numbers/

GM sells twice the Silverados as Cruze - and has turbo option on a VVT engine.

http://www.drivenracingoil.com/news/dro/...s-on-motor-oil/
http://www.knowyourparts.com/technical-articles/phaser-style-variable-valve-timing-systems/

VVT engines do not 'just work fine' on conventional oil - thats why they changed the standards

http://www.autoblog.com/2010/10/02/gm-engine-oil/

Scroll down to the part where it says "The dexos oil also has some unique properties that General Motors engineers required. One characteristic is better resistance to aeration (the whipping of air bubbles into the oil). Some GM engines with variable camshaft timing use engine oil as a hydraulic fluid to move components within the engine. If air bubbles are in the oil, components actuated by engine oil will not move as they were designed to, limiting engine performance and efficiency."

Now would you like to answer my original question?

 

[WobblyElvis]

The GM OLM is supposedly adjusted for each type of vehicle they make. How much research they do to make it accurate for any particular vehicle is anyone's guess. I very much doubt the code is written to alter your OLM just because you tell a dealer you are using a better oil. It would not be in GM's best interest to alter your OLM and open themselves up to a possible warranty claim.

I like the OLM on my car but I don't think of it as perfectly accurate. For one thing, it doesn't account for engine wear. Used oil analysis has shown my OLM to be extremely conservative and I regularly exceed the OCI it recommends. If you want to want to alter your OCI from what the OLM recommends the only thing to do is pay for a UOA and work from there.

 

[NH73]

Originally Posted By: WobblyElvis
The GM OLM is supposedly adjusted for each type of vehicle they make. How much research they do to make it accurate for any particular vehicle is anyone's guess. I very much doubt the code is written to alter your OLM just because you tell a dealer you are using a better oil. It would not be in GM's best interest to alter your OLM and open themselves up to a possible warranty claim.

I like the OLM on my car but I don't think of it as perfectly accurate. For one thing, it doesn't account for engine wear. Used oil analysis has shown my OLM to be extremely conservative and I regularly exceed the OCI it recommends. If you want to want to alter your OCI from what the OLM recommends the only thing to do is pay for a UOA and work from there.


I agree with that. I doubt GM would adjust your OLM to Dexos1 standards, when there Owners manual says you can use conventional. For all you know, 2010 and 2011 Silverados OLM's may be the same. I don't know, someone who has better knowledge would need to say. But if they aren't. Like WobblyElvis said, your only option would be to do UOA's and decide what works if you want to run snythetic.

 

[Garak]

When does your OLM typically go off on your truck, after how many kilometres? M1 and Castrol Syntec will give you something like a 15,000 km warranty up here on their oil change intervals.

As for VVT and oil aeration, while it certainly might have been a concern, GM could have skinned that cat in a multitude of other ways. The dexos1 spec just made it a little more logistically sensible to attack several issues and try to make things a little easier on the consumer. Now, with their being several dexos1 viscosities, I'm not so sure.

I can't see a 5w-30 dexos1 oil being more robust than any 5w-30 A1/B1 A5/B5 oil on the shelf. It's just that most people have enough trouble with the 5w-30 part of it, let alone looking for an ACEA certification.

 

[phatcatz]

Well to put some sort of line under all this - here is what I've decided to do.

As in my original post - I'm not the type to keep looking at the odometer. The OLM is great for a guys like me - I'll just keep changing the oil when it tells me to - even with the synthetics.

I'm going to stay with synthetics because:

• I now realize that I should be running something up to the Dexos spec.
• Winters get cold here where in live in Canada with a least one -40°C night, and sometimes a week of severe weather.
• Summers are often hot - with at least 2 weeks of +30°C
• I live in the GTA which means a lot of stop and go driving.
• I often trailer my boat and transport heavy loads long distances (it is a pickup truck)
• I'd like to get another 5 years out of the truck. With the odometer now sitting at 198,000km, that means I'm looking at a possible 400,000km before trade.

Still don't know if there is any difference in the OLM algorithm between a Dexos engine and a non Dexos engine, but I found out today that GM changed the part number for the oil filter for my truck - which always means there was an engineering change - and most likely to deal with the Dexos spec change.

 

[Blinker]

Dexos was a result of DI and turbocharging.

 

[Blinker]

It has been suggested that its best to run synthetic in the 5.3 because of the AFM. less chance for the rings to coke up and begin burning oil.

 

[Blinker]

I believe the 2011 5.3's had some internal changes due to the oil burning problem in the 2007-2010 because of AFM. I believe that is why you oil filler neck is different. To my knowledge, 2011 was the 'update year' on that engine.