I have come to the conclusion that regular old Chevron Supreme 5w-30 (GF-5/API SN) that you can get at Costco on coupon for $27.99 per case is not much different than the expensive synthetic oils on the market in terms of wear reduction. Thanks to the Chevron banner at the top of this forums page, I found I can get a $5 per 5 quart purchase rebate up to $15. (15 quarts)
As you can see in my signature, my vehicles are 2008 and older, the Dexos standard didn't start until 2011 model years. Through analyses I have found the wear metals are no higher using Chevron Supreme for the same mileage as expensive synthetic oil. The oil I tested against was Redline, at the time around $12 per quart. I had to do 3 oil changes to get all the residual oil out from previous oil types. I figure for the same (or less) money, I can change out the Chevron every 1k-2k miles and still be ahead of leaving the Redline in for 5k. 5k is when analysis showed the oil needed to be replaced.
I am finding Milesyn SXR 5w-30 licensed Dexos 1 (not Gen 2) (5 gallon pail) on Amazon for $65.87 + tax, free shipping. That is about $3.59 per quart. If I buy 2 cases (24 quarts) of Chevron Supreme at Costco (to get the $15 rebate), it's about 2.00 per quart with the $15 rebate. Milesyn also has a Synthetic Blend 5w-30 that meets GF-5/API SN for $39.98 + tax per 5 gallon pail, that works out to $2.18 per quart. The Chevron price is slightly higher due to CA adding an "oil fee" of 29c per gallon. I don't know if Amazon is adding this fee.
My question is now that the synthetic Dexos 1 is available at a more reasonable price, is the benefit really there? The non-rebate price of the Chevron works out to $2.62 per quart, so for less than $1 per quart, I would be upgrading to Dexos 1. Of course, the Milesyn GF-5/API SN would be cheaper than the Chevron. The GM requirement for these engines is 6094M, which is met by GF-5/API SN products.
The product specifications for the Chevron Supreme are actually better than the Milesyn SN.
To Dexos, or not to Dexos, that is the question.........