It’s a wonder it doesn’t break with every cold start.
Towing with GM Light Duty 3.0L diesel
- Thread starter rbk777
- Start date
- Joined
- Sep 20, 2021
- Messages
- 13
Switched out to Mobil 1 Dexos 2 5W-30 two changes ago. First two were Dexos D. No concerns about going to a 5W-30 since GM has an approved oil at that vis that they aren’t marketing yet. Have never done any UOA on any previous vehicle but might at 20k just to see. That’s a ways off, though. We’ll see.
Where have you seen they have a 5w30 dexos D? Just curious? I just wish we knew the requirements of dexos D.
No that’s not what he’s saying. dexosD cannot be a 30-grade per the low HT/HS and the licensing requirements.
By definition DexosD is going to be a 20 grade, it's GM's rebrand of ACEA C5 which stipulates the HTHS viscosity be between 2.6-2.9 which means it's Xw20
Yeah I just read his statement that said GM has an approved oil at this viscosity they aren’t marketing yet. As him referring to dexos D
Yep. I assumed it was their money grab at c5 but they haven’t released the official requirements to meet dexos D.
The only Wierd thing I found is amsoil now sells 5w30 that “meets” dexos d
Hths of 3.5
Amsoil loves to claim they "meet" specifications that their oil doesn't actually carry, they have in the past exceeded constraints set by manufacturers or the API and still recommended their oil for use where those classifications and approvals were specified, take an Amsoil recommendation with a grain of salt.
I did find the actual specification online somewhere, apparently they did addend the spec to add a 5W-30 with an HTHS between 2.9-3.5, but there are currently on DexosD licensed 5W30 oils and no vehicle calls for that viscosity grade and DexosD, and essentially Amsoils DexosD is a little contradictory, it says it's also Dexos2, Dexos2 should have an HTHS more than 3.5 while DexosD should have an HTHS less than 3.5, which makes an oil that claims both contradictory.
- Joined
- Sep 20, 2021
- Messages
- 13
Search GMW18006. GM Dexos D 0W-20 and 5W-30.
So who’s going to pay for it and make it public for all of us
Someone who is willing to put themselves at risk of legal action.
At the bottom of every page (among other things): the purchaser's name, license serial number, date/time of access, and the text "Reproduction, distribution or publication of these standards is expressly prohib" [sic].
Sorry to be the bearer of bad news. GM can be very protective of their specifications.
Hint:
It's possible to interpret that revision description in two possible ways, and you assumed the wrong one
- Revised HTHS for 5W-30 engine oil from 2.9 to 3.5 (it used to be 2.9, now it was revised to 3.5)
- Revised HTHS for 5W-30 engine oil from 2.9 to 3.5 (it has been revised, and now it's a range from 2.9 to 3.5)
GMW18006, 3rd Ed., Nov, 2020
Description / Abstract:
GMW18006, 3rd Edition, November 2020 - dexos D Diesel Engine Oil
Note: Nothing in this standard supercedes applicable laws and regulations.
Note: In the event of conflict between the English and domestic language, the English language shall take precedence.
Purpose/Material Description.
This specification details the materials and performance requirements of dexos® D 0W-20 and 5W-30 diesel engine oil.
...
Let's hope and shoot for 5W-30 oils with an HTHS of 3.5 . It's right on the money. And for those out there that said GM would eventually relent and issue a spec for a higher viscosity oil (and subsequently higher HTHS), you were right.
As soon as the reflash 22 trucks show up with the higher towing ratings I’ll be sure to check out of the new diesel supplements and see if they mention the 5w30 spec
I can’t imagine that they are specifying a range. Do you know of any other license or approval that gives a range? Of course it may be in this case because of whatever reason, but I’ve only seen ones that specify a minimum.
But then again if this license gives two different grades then you don’t have much choice. I can’t see how you’d straddle both here.
Having read the spec myself, I can confirm it does not conflict with SAE J300. In other words, they are in fact minimum values, not ranges.
A little late to the party but personally I like the Castrol 0w30. Historically it's been a solid oil but admittedly not quite the same as before. Made in Belgium I believe, if that means anything to you.
