Originally Posted by Mr.MichaelM3
I highly recommened not doing this. I was on vacation this past Friday. I drove to lake george about a 200+ mile drive. Anyway Within the first 30 mins of driving my oil light came on. I called my buddy SAL@AUTOcouture and he said it's better to just ride it out till I got to a local BMW dealership than to put ANY OTHER OIL that is not recommened for our cars. Especially 10w30. However I feel your pain as I was also thinking about doing the same but I drove about 400+ miles all together with just a quart low of oil and no issue.
That logic is ridiculous. The addition of one quart of lower viscosity oil will impact the overall kinematic viscosity of the oil (generally around 8 quarts) a negligible amount. Consider that versus the oil pump firing air into your bearings while going around a corner.
I'll add my extra quart of non-10w60 thanks. BTW, oil analysis indicates that the oil quickly shears to a 40wt at operating temps anyway, so the overall viscosity change is even less.
By the way, the manual states that small quantities of non-oem spec make-up oil can be added without issue.