After checking the manual for oil recommendations for my 2021 C8 it states to replace with Mobil 1 0-40 w Dexos 2. I thought I saw somewhere on the forum that Dexos 3 was the replacement for the 21 C8 now. Is that true? Can I put Dexos 3 in my 21 C8? Thx

 

dexosR is the replacement for dexox2 in gasoline engines. In a 2021 you can use either dexos2 or dexosR. Mobil1 is currently the only supplier of 0W40 dexos2 (ESP X3) or dexosR (Supercar) oil for C8 Stingrays.

 

RKCRLR is correct!!

Not a big deal to use either but why not go the latest and greatest, dexosR, 0W-40 Mobile-1 Supercar oil.
People on the forum just shown that you can get it on Amazon.

 

Mobil has confirmed that Dexos R Supercar 0W-40 is identical to Dexos 2 ESP 0W-40, and is nothing more than a rebranding. So if you run across a good deal on the ESP, don't hesitate. It's just as "latest and greatest" as Supercar.

Using the ESP X3 in your 2023 or later isn't going to hurt anything either.

 

The geniuses at GM made Dexos 2 the spec for light duty Diesel engines after spec-ing it for C8 Corvettes, and the stuff for us is now Dexos R. GM doesn’t think anyone will read the manual I guess. Seems like GM should have to issue updated manuals when something like that is changed.

 

GM says that the dexos 2 is discontinued in the 2025. Vehicles with diesel engines that required dexos 2 will use dexos D. Vehicles with gasoline engines that required dexos 2 will use dexos R.

Here is the exact wording from the gmdexos website.

"Please note: GM dexos 2 is being discontinued in 2025 and replaced by GM dexos D and GM dexos R. Vehicles equipped with diesel engines that used GM dexos 2 engine oil will use GM dexos D licensed engine oils, while vehicles equipped with gasoline engines will use GM dexos R licensed engine oils of the of the appropriate viscosity grade at their next oil change." and "Please note: GM dexos R engine oils meet or exceed the performance of GM dexos 2 and GM dexos 1 Gen 2 and Gen 3 oils and are backward compatible, therefore vehicles equipped with gasoline engines that used GM dexos 2, or GM dexos 1 Gen 2 or Gen 3 may use a GM dexos R licensed engine oil of the appropriate viscosity grade at their next oil change."

The gmdexos site currently lists 99 motor oils that are licensed under the dexos 2 specification. I checked several and the ones I checked are recommended for passenger cars, light trucks, gasoline engines and diesel engines. Mobil 1 ESP x3 0W-40 (not to be confused with Mobil 1 ESP Formula 0W-40 which became Mobil 1 Supercar 0W-40), is dexos 2 rated and compliant with the 2020-2022 Corvette Owners Manuals, but was actually developed for European gasoline engines according to Mobil 1: 'Mobil 1 ESP X3 0W-40 is our latest technology developed in cooperation with Porsche, one of our key European Original Equipment Manufacturers (OEMs). Mobil 1 ESP X3 0W-40 has been expertly engineered to help prolong the life in new emerging gasoline powered European vehicles." There are articles out there that say "GM designed dexos 2 [which is only a specification] for light duty diesel engines" but the fact is it is recommended for use in some European gasoline engines. Note that Mobil also says vehicles equipped with gasoline engines that used GM dexos 2, or GM dexos 1 Gen 2 or Gen 3 may use a GM dexos R licensed engine oil of the appropriate viscosity grade [if there is one - right now only two are made 0W-40 and 5W-50] at their next oil change.

 

Initially dexos1 was for gas engines and dexos2 was for light duty diesel engines and then GM decided to use it for Corvettes. They are just trying to get back to keeping the diesel engine requirements separate from the gas engine requirements.

 

Nearly nothing but nutty marketing. I spent quite a while digging through Mobil's and assorted tech-related sites to try and make sense of this gobble-de-gook.

 

Dexos 2 (and now Dexos D) have a much lower ash content than Dexos 1 oils because that's important for diesel exhaust particulates. I suspect the reason GM spec'd a Dexos 2 formula for the C8 was because of the intent to sell it in Europe, where exhaust particulate filters were being mandated. Low ash content is important to prevent those particulate filters from getting clogged.

 

What oil is need for a 2023?

 

0W40 dexosR (Supercar) oil is specified for 2023 and later Stingrays.

 

dexos 2 and dexos R are motor oil specifications developed by GM, not products. GM then requires that motor oils meeting a certain dexos specification (dexos 1 gen 2, dexos 1 gen 3, dexos 2, dexos D , or dexos R) be used in cars that they manufacture (in the US or abroad). Any oil producer can submit a product to GM for testing and monitoring - once licensed under a dexos specification that product can show "dexos® icon on the front label and the 11 digit alphanumeric dexos® license number on the back label." In their own words, GMs motivation for writing their own specification is this:

"GM has found that using substandard oil can affect engine performance and, in the worst case scenario, may damage or harm the engine. Only licensed dexos® products have been certified by GM to meet the dexos® specification. Unlicensed products have not gone through GM's rigorous testing process, are not monitored for quality, and are not approved or recommended for use in GM vehicles. Unlicensed product quality and suitability for GM vehicles cannot be guaranteed and, therefore, use of unlicensed products may result in lower levels of performance and could cause engine damage that may not be covered under warranty."

As I mentioned earlier, I count 99 different motor oils licensed under dexos 2, and 36 different suppliers. Of those Mobil 1 (Exxon Mobil) supplies 10. Chevron (Havoline) supplies 9. Castrol supplies 13. Interestingly, GM is listed as supplying 11 different 5W-30 motors oil, 10 with an ACDelco name, and one called Pecas Genuinas GM Sintetico, The remaining 56 motor oils meeting dexos 2 are made by the other 32 suppliers (some familiar names, some not so much).

While GM may specify a dexos approved motor oil for cars it delivers to the European market (Corvette being one of them), I do not know if other European car makers also invoke a dexos requirement. They might, but European car makers (like Porsche, Mercedes Benz, VW) can and do write their own specifications as well. For example besides meeting dexos 2, Mobil 1 ESP x3 also meets Porsche C40, MB229.51, MB229.52, VW511 00, according to the Mobil 1 product data sheet. The Mobil 1 Supercar 0W-40 pds currently only lists dexos R under Specifications and Approvals.

So, given that dexos 2 is just a specification, what exactly does it mean to discontinue it? I assume GM will stop accepting oils for certification under the dexos 2 spec, but do the licenses granted under the dexos spec expire? What happens to all of those dexos 2 licensed motor oils? Do they just stop displaying the dexos 2 icon. Do they submit the product for approval under dexos D or dexos R as appropriate? What happens to Mobil 1 ESP x3 0W-40 in particular - it is specifically for gasoline engines, not diesel (according to its pds). Will it be approved under the dexos R spec? Although we know that Mobil 1 ESP Formula 0W-40 which was licensed dexos 2 became Mobil 1 Supercar 0W-40 licensed dexos R, it does not mean than all dexos 2 motor oils for gasoline engines will meet the dexos R requirement.