Dealer Supplied Synthetic Blend Oil

[goldie]

I recently had my 07 Sierra serviced at the dealer where I bought it. I was told the dealers are now using only synthetic blend of oil for oil changes. The service tech could not tell me what the blend was other than being 5w-30 Dexos. Two (2) email later to the dealer and all I got back was a song and dance about the service they provide, etc. but no answer on what the blend of oil. I contacted the GMC Customer Assistnace Center and was unable to get an answer. I was told they would have to research it. All I want to know is what is the blend (%) of synthetic oil to regular oil. Can you help?

[RayVoy]

All I want to know is what is the blend (%) of synthetic oil to regular oil. Can you help?

I suggest you will have a hard time locating that info.
Here is the GM information, along with a list of approved 3rd party oils: http://www.gmdexos.com/home.html

I suspect the formula for each "mix" is proprietary information. Go with the full synthetic and avoid the worry.

[Pikey]

Good info Ray. I guess I know why the GM tech center switch from mobile one to FUCHS. I have been running the fuchs TITAN Supersyn D1 SAE 5W-30 for the last few oil changes.

[RayVoy]

I just switched from Castrol Edge to Royal Purple, I don't see RP on the list.

[Pikey]

what is funny is that less than 2 years ago GM was using royal purple at the tech center.

[goldie]

@RayVoy -Thanks for the great information. I checked the site and was very pleased to see all the options for oil. I'm going to keep plugging away and if I get an answer will post here and any other thread anyone can suggest as being appropriate.

[goldie]

Well, the GMC Coustomer Assistance Center replied to me and the told me they could not find the information. I sent a message through the site RoyVoy supplied and they have not replied. And, of course, no reply from the GM Customer Service folk at this thread. I truly don't know what the big deal is about this oil.