Originally Posted By: micmac
I have had good luck blending 4:5 TGMO 0w20:Mobil 1 0w40 FS. This will give you a nice 0w30 with a much higher VI than Mobil 1 AFE 0W30 and a nice high TBN and SAPS for extended drain intervals. Credit to Caterham for the recipe.
It will give you something, as Shannow noted, with a 30 rating when hot. You have no idea what the CCS/MRV performance is, but given the group III content of TGMO (it is entirely group III based) and Mobil 1 0w-40 FS being GTL-based, the PPD's are being diluted in a base that doesn't require PPD's, reducing their effectiveness for the base that does require them (group III). Ergo, you have no real idea what the W rating for the finished mix is going to be nor do you really know what the VI is going to be either, given you are again diluting the VII's from various base mixtures with each other, which completely skews the treatment mix and results in ?????
Ultimately, without putting the "mix" through the requisite testing, the best that can be claimed is that it will not cause damage. It cannot claim superior performance by any metric without being properly vetted through the protocols the mixed constituents were subjected to during their individual developments and approvals.
It is incredibly naive (or pompous depending on how the claim is being made) to believe one can create a superior end product by mixing two fully formulated lubricants together. The chemistry involved essentially prohibits this. Each product is a rigorously tested compromise in a huge host of areas, including cost, in order to meet specific performance criteria. A Euro 0w-40 and an ILSAC 0w-20 are worlds apart in terms of the OEM test protocols just to scratch the surface of those development processes. Ergo, mixing two chemical compromises together results in yet another compromise, but one which has not been tested for the applications that either individual product has. You create what is essentially an unknown with the only guarantee being that it won't separate and that whatever the resulting chemistry is, it is no longer optimal.
I'm not a fan.