Originally Posted By: Pop_Rivit
Originally Posted By: JHZR2
Another question that might come in to play is what is the vehicle and what is the use profile?
The vehicle(s) I'm currently considering are 2008-2009 Cadillac STSs and DTSs. It will be my daily driver, and also used for long trips. Almost all of the miles will be highway miles.
Originally Posted By: JHZR2
End of the day, I doubt that $2/qt, which is maybe $10/OCI is going to have a major effect on lifecycle cost given that it's the equivalent of burning maybe four gallons of fuel over an OCI.
True, to an extent. But I try to cover all the bases and get a solid handle on the cost of ownership so I know what to expect and plan for. It's part of the due diligence that any owner should do before making a purchase. Especially since we're judicious with our finances and know where pretty much every dollar goes.
So it appears that dexos 1 supersedes the 4718m spec as well as others, such as the LL-025-A spec that my Saab requires. Looks like 4718 was primarily related to volatility and oxidative thickening, though it's not clear if these are more or less stringent in dexos 1 vs 4718.
I'll say this, for my Saab, which does two year, 15k mile OCIs by design, and required the LL-A-025 spec, I've stayed running M1 0w-40 over dexos 1, simply because Mobil recommends that oil for Saab and it retains plenty of other rigorous specs. I would suspect that given the focus on turbocharged, long life extended drains, that the ability to combat oxidative thickening (like 4718) would be there. So you might want to consider an oil like the M1 0w-40.
That said, dexos 1 is claimed by gm to be a suitable replacement for the 4718 spec, and you have a car with a fairly big and powerful v8, which though on a heavy car, is probably rather under-stressed in the rather benign highway use you mention. So any cheap(ish) dexos 1 oil would probably do just fine.
But I still suspect that fuel and other costs are going to so dwarf the delta in oil prices that trying to get your pencil sharp enough to eek out the small delta in cost is going to create a situation where "perfect is the enemy of good enough", and you'll just be wasting time. If being judicious with the finances is a big deal, your old Elantra is probably a far better lifecycle cost choice, as compared to a big V8 luxury/performance sedan. 25 MPG is roughly 10c/mile. A $10 difference in oil prices over a 3k mile oci is only 0.3c/mile, and I suspect your OCIs are longer than 3k...
