Don't worry, I'll let everyone know if the smart blows up....
You're in Ohio, so if you do go above 86*F it probably won't be by more than the margins they spec'ed into the shift points. Now, if you were to go for a 4th gear highway run on a 95*F day, then get back into town and back to auto mode, that would probably be very bad...
I use 0W30 myself, I'm just careful with the revs on hotter days.
Now I am getting even more confused (between jwights chart & evilutions chart) LoL! Because if I can use a 5w-30 or even a 10w-40 then I can get those for a much lower price then do the change @ every 5,000 and be fine with that...BUT now what about semi-synthetics? I ask this simply for the reason that my local shop does a semi-synthetic 5w-30 oil change for $9.99! Now, I am not trying to be "cheap" (as I don't mind paying for confidence,safety and security) but since I will be doing a minimum of 500+ miles a week my oil change schedule will be a lot more often than most and being frugal/economical in these times is not the same as being "cheap".
10W40 will be just as good as 0W40 as far as engine wear goes (at least in your climate), but if you use the 10W then your fuel economy will really suffer until the engine gets warmed up. Much more of an issue if you make lots of short trips, as opposed to fewer longer ones.
I'd still stay away from 5W30, but it's your car.
I'd also stay away from semi-synth, but I'm not nearly as opinionated on that as viscosity. Chances are you'd never know the difference for using it... it'd just be more wear of the gradual sort.
Some of the earlier documentation stated that they were 10.0:1, but I have yet to see anyone present actual evidence (different part numbers across the model years for pistons, rods, etc.) to indicate that this discrepancy was anything other than an erroneous figure in the manual.
Even if the earlier US-spec cars were in fact delivered with a lower compression ratio, the change would not necessitate a different oil specification from that of the ROW cars running a higher compression ratio. And as the higher compression ratio began being listed in the literature at least as early as 2011, it would certainly offer ample time to "update" the oil chart accordingly to ROW-specs if that were indeed the reason for the original modification to the 30 weight values.
Larry's screaming cow got to 23 lbs of boost on stock internals before it blew up, and when it did it wasn't because of knock, burned valves, preignition, or anything like that... it was just that a compression ring wasn't sized right for those temperatures. As far as I've heard, there aren't many engines out there with normal
9.x:1 compression ratios that can take that kind of boost on stock internals. An 11.4:1 engine that could handle abuse like that would be quite a feat indeed.
To put things in perspective: 22 lbs = 1.5 bar, so 2.5 atm absolute... 2.5 * 11.4 = 28.5... 28.5 / 9.5 = 3 atm absolute, so 22 lbs @ 11.4:1 is roughly equivalent to 30 lbs @ 9.5:1, except it's even crazier than that since a bigger percentage can be intercooled on the lower compression engine.
Do you know of any originally N/A engines that can take 35 psi boost on stock internals?
The chart on Evilution's site is the one smart has provided outside of the US for a number of years.
If you have difficulty accepting that Mitsubishi somehow re-worked the 3B21 exclusively for the US market in such a way as to require different lubrication than the engine it provides to smart for the rest of the world, then the Evilution chart is fine.
You might also be interested in learning that it had previously been determined that Mitsubishi delivers the engines to smart filled with a non-synthetic oil (most likely 5W-30).
Mitsu most likely doesn't do the ECU/TCU programming. The ECU is Bosch, the TCU is most likely Getrag. There's a lot of room for difference there... did that source mention if MB changed the oil before sending them out?