Is GM’s Dexos 2 requirement for the LT4 on the C7 Z06 and CTS-V strictly emissions based?

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Hello everyone! Long time lurker here but I finally made an account to ask my own question.

I have a 2016 Cadillac CTS-V with the LT4. GM spec calls for a Dexos 2 approved oil and recommends the Mobil 1 synthetic 0w40 ESP which has recently been relabeled “supercar”. I’ve been running this oil thus far per factory recommendation. I ran the same on my modified C7 Z06 I just recently sold.

The “ESP” stands for “Emissions Systems Protection”.

My question is… With emissions equipment removed, is there any longer a necessity to run the Dexos 2 spec?

My understanding from my research is… Dexos 2 calls for an ash level equal to or less than .8 (as protective measure for emissions equipment).

Is there other reason beyond that as to why the Dexos 2 approval would be required on the DI engine?

Reason I ask… my car is heavily modified with Heads/cam/Whipple, full bolt ons, etc. Emissions equipment is no longer a concern. I also live in Houston, TX where summer temps get higher than most. Considering my car sees some spirited driving and I do frequent oil changes at approx 2k mile intervals due to using E85 and meth, I have been contemplating the switch over to Rotella T6 5w40 or something similar that’s a slight bit heavier and more readily available.

Anyone see an issue with that? I assume the T6 will have a higher HTHS strength and likely higher zinc content as well. The T6 has a 1.0 or lower sulfated ash level. That’s only a .2 difference. It’s also pretty convenient that it can be purchased at Walmart at a cheap price. If emissions are the only purpose for the Dexos 2 requirement, I’d imagine at this point, I should be able to use any good quality oil I want. Just looking for the best protection vs a strictly emissions focused oil as that no longer matters on this vehicle.

I figured this would be the best place to ask this question. Looking for someone with some expertise that can look past the owners manual considering it to be gospel. I asked this question on a facebook V page and a couple people said it would be just fine but… most of the others seem to be anti anything that’s not recommended by GM and they think the car will implode if you use anything aside from the recommended Mobil 1 0w40 ESP.

Let me know your thoughts. Thanks in advance!
 
I have the LT1. For these engines, the track supplement also allows M1 15w50 for the LT4 but advises to change it out after a track day. This is purely for warranty on the emissions system. Based on your mods, I would use M1 15w50 weather permitting or M1 Euro 0w40 if you have no emissions system. Another consideration which I used for my first oil change is M1 ESP x3 0w40. There is an autozone bundle deal that makes this oil around 6 bucks a quart. This oil is a dexos2 oil, but it also carries Porsche C40 approval. Also, the LT4 is dual injection, so no DI intake valve concerns. I'd definitely consider M1 15w50 especially since its inexpensive and beefier for the e85. No downside.
 
My question is… With emissions equipment removed, is there any longer a necessity to run the Dexos 2 spec?
No, in fact, use some caution as many modern oils have lower levels of additives and reduced HTHS. Today's oils are not "better than ever" they are simply engineered for a specific purpose. It is my opinion that using as little as 1/3rd the prior level of additives, then employing an additive conserving, AN base stock is not the way to produce more robust oils.
 
there are many "recommendations" based on $$$$ especially in USA + Uncle Sam + others carry a lot of CLOUT! well spoken by CuJet! our country is still the BEST but IMO its going DOWNHILL!!
 
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Welcome to BITOG 🥳

Originally, GM called for dexos1/d1g2, but they later charged it to dexos2 (which they otherwise reserve for diesel engines and Europe) which is usually thicker (HTHS 3.5+).

Walmart does sell a dexos2 oil, PP Euro L 5w30, at a good price :)

GM's dexos standards probably account for E85 use, since they push E85 flex fuel more heavily than anyone else.

Maybe you could try the regular M1 0w40, which is popular as a trackday oil on many cars :unsure:

The warranty is probably void from the modifications anyway :sneaky:
 
I will say no. Dexos-2 is a high(er) HT/HS oil with the requirement being greater than or equal to 3.5cP@150ºC. It is specified in many light duty diesel and high performance gasoline engines and is/was actually a common standard for European vehicles when GM owned Opel/Vauxhall.

While the additive package is designed to afford longevity to the emissions components, the oil itself carries a higher dynamic viscosity than what GM generally specifies for their North American fleet. With Dexos-2 (Dexos-R) you get an emissions system friendly high performance oil.
 
I appreciate the responses guys! I’m sure the ESP is a quality oil. I don’t doubt that one bit. I just typically like to run a readily available oil I can grab local if I’m in a bind. I’m coming up on oil change time again and after doing some digging, started thinking if the Dexos 2 is emissions focused only, I might as well swap to Rotella T6 5w40 as that’s what I run in majority of my other vehicles. Easy to find and has a HTHS of 4.0 which is even better than the 3.5. Of course there are other variables to consider that are over my head from an engineering standpoint.

My typical go-to oil on my prior performance cars (built motor cars mind you) was always the Valvoline VR1 20W50. But… tolerances are a little difference at that point. It might be ok in the LT4 as they recommend the 15w50 someone else here mentioned for track use but it’s still a stock bottom end car. It’s just a weekend driver. It doesn’t get many miles put on it annually.

I just thought maybe there was a better option to resist the abuse than the 0w40 ESP a stock vehicle would stick with. No concern with voiding warranty as that was voided long ago. 😂
 

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Does anyone here with an LT4 car use the red cap 15w50 Mobil 1 synthetic they recommend for track only as a year round fill? I just figure if the car is a weekend toy with mods and it sees some abuse, that might be a solid option… especially here in Houston, TX. I’ll have to go see what the Dexos rating is on it just out of curiosity. Only difference I could see is having to make sure the oil is good and warmed up with a longer idle before driving it in cooler weather (40’s-50’s currently right now). Wouldn’t want to just fire and go (which I don’t do anyway).
 
We all have an opinion, so here is mine. I'd stick with the Mobil brand but go with one of their HDEOs like Delvac 0w40 or 5w40.
Another option is Mobil-1 10w40 motorcycle oil. Why? Because I read on the internet that HDEOs and MCs have a more shear stable
viscosity modifier, in addition, as a group, are a little thicker than PCMOs of the same grade.
 
We all have an opinion, so here is mine. I'd stick with the Mobil brand but go with one of their HDEOs like Delvac 0w40 or 5w40.
Another option is Mobil-1 10w40 motorcycle oil. Why? Because I read on the internet that HDEOs and MCs have a more shear stable
viscosity modifier, in addition, as a group, are a little thicker than PCMOs of the same grade.
I posted this on the wrong Cadillac thread;

10w40 motorcycle SN
5w40 Delvac CK-4/SN
0w40 Delvac CK-4/SN

Add; 5w50 Supercar for the new Corvette DexosR/SP
 
I posted this on the wrong Cadillac thread;

10w40 motorcycle SN
5w40 Delvac CK-4/SN
0w40 Delvac CK-4/SN

Add; 5w50 Supercar for the new Corvette DexosR/SP

Some solid options! Didn’t even realize they had a 5w50 supercar as an option. I’ll have to look into that. Might not be a bad move.
 
Some solid options! Didn’t even realize they had a 5w50 supercar as an option. I’ll have to look into that. Might not be a bad move.
Moi oci. I knew about the 5w50 racing and 5w50 FS X2, but not the Supercar.

Of the xW40s I like the 0w40 the best with its 4.1 HTHS.

edit; Do you still have the ehaust cat? If you remove it, you'll have to fool the downstream O2 sensor(s).
 
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Moi oci. I knew about the 5w50 racing and 5w50 FS X2, but not the Supercar.

Of the xW40s I like the 0w40 the best with its 4.1 HTHS.

edit; Do you still have the ehaust cat? If you remove it, you'll have to fool the downstream O2 sensor(s).
I knew about the Mobil 1 15w50 but didn’t know they had a 5w50. Learn something every day.

Which 0w40 has the 4.1 HTHS? The 0w40 ESP/Supercar shows 3.5.

No. The car is heavily modified at this point. Emissions have been removed and car has been tuned with the rear o2’s being deactivated.
 
I knew about the Mobil 1 15w50 but didn’t know they had a 5w50. Learn something every day.

Which 0w40 has the 4.1 HTHS? The 0w40 ESP/Supercar shows 3.5.

No. The car is heavily modified at this point. Emissions have been removed and car has been tuned with the rear o2’s being deactivated.
The Delvac 0W40 CK-4/SN shows 4.1 HTHS, which sounds about right.
Before the re-branding of ESSO/Imperial OIL products to Mobil, ESSO XD-3 0W40; KV100C was about 15.5, BN 13, SA 1.5 & CH-4.
 
I knew about the Mobil 1 15w50 but didn’t know they had a 5w50. Learn something every day.

Which 0w40 has the 4.1 HTHS? The 0w40 ESP/Supercar shows 3.5.

No. The car is heavily modified at this point. Emissions have been removed and car has been tuned with the rear o2’s being deactivated.

You have a heavily modified car, my advice would be to call Dave at HPL and get his thoughts!
 
This stuff isn’t priced too bad and looks pretty good. I know they have a DI40 that’s a 0w40 and a DT40 also. I’d have to read the specific differences between each but I’ve heard good things about this driven oil.
 
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