You can't go wrong with using either oil. The 5w40 came along with the 229.5 MB specification, which primarily applied to those newer model years that could use an extended oil change interval over the 229.3 spec that covered the FSS oil tracking systems used on earlier MB models. The Crossfire uses the MB FSS oil tracking system, probably because the Crossfire is designed using the R170 MB chassis which was the outgoing model in MB. But the Crossfire engines weren't necessarily 'older' versions. Most likely a political issue between MB & Chrysler back then.

Another difference between the 2 specs is the 229.5 required the owner to use the 'fleece' type oil filter over the 'cellulose' version. You will see where I highlighted that requirement in the attached file. Most of us use the 'fleece' type filter in our cars anyway, which probably has better filtration characteristics than the cellulose version.

Another consideration for you, since you live in Florida is to use the 5w40 oil, which would have a slightly higher oil viscosity during cold start-up. Is the difference significant - I don't believe so, but it is a difference. I live in SC, which isn't much different than Florida, & I use the 0w40 product. Kind of interesting to see that the 0w40 motor oil has a higher viscosity at 100C than the 5w40 product. Probably due to the 0w40 additive package which maintains the oil viscosity across a wider temperature range. Goes against traditional thinking which I stated at the beginning of this point.