I agree that there are quite a few synthetic alternatives out there which we can use rather than Mobil 1. In fact, as stated earlier in this thread, we've hashed this quite a few times already and I personally have posted documents similar to those in Bladecutter's post that list all the oils approved that are typically marketed & distributed in the US.

What is interesting is that nearly all of the 5w30 synthetics approved for M-B 229.5 & 229.51, which are listed as alternatives to Mobil 1 European 0w40 or Mobil 1 ESP 5w40, are shown not approved for an AMG engine! The viscosity of these oils at 100 deg C is well below that of the Mobil 1 products and M-B warns to stay clear of them for these high performance versions of the motors. So, according to the info posted elsewhere in the Forum, using something other than Mobil 1 in an SRT-6 might be a risk an owner has to decide to take. For us with NA models, not really an issue. The products from Pennzoil, Shell, Quaker State, Castrol, etc., all are approved.

It is worth noting that the synthetics listed as approved alternatives (typically 5w40 grade) to Mobil 1 European 0w40 for M-B 229.3 all seem to have viscosities at 100 deg C that exceed the specs of their comparable products (5w30 grade) shown as approved for M-B 229.5 & 229.51. Why aren't these listed under M-B 229.5 & 229.51? The only difference I see is that the 229.3 oil (& 229.5) is approved for use with the FSS (Flexible Service System) that's on our XFires and the 229.5 & 229.51 oil is shown as compatible with M-B's MMS (Mercedes Maintenance System) which is on other vehicles. Not sure what the differences in the 2 systems are that led M-B to this position. Does anyone know anything further about this? Curious minds want to know.

But for me, at nearly every self-serve auto parts house near me, Mobil 1 will be less cost than the other brands, day in & day out. And I'm old enough to remember when this wasn't the case!!!! But as cajunfire started with this thread, there are sales every once in awhile that are worth passing along. Thanks for the tip.

FWIW - The last time I looked into it, ExxonMobil had the contract with Walmart to supply the automotive motor oils. So Walmart's synthetic is some derivative of Mobil 1. I use the Walmart brand in some of my other vehicles and it's always less cost than anyone's brand name synthetic.