The best engine oil viscosity for the 355

I am no expert, but i believe 10/60 is more suited for when you are tracking the car

 

I run 0w40 mobil 1 on the street. I ran it at the track but when oil temps went over 230F, the oil pressure was a little lower than I'd like (70psi instead of 90), so plan to run 15w50 at the next track event. It's never an issue on the street or at autox, oil doesn't get hot enough to need a heavier oil.

 

Truth ^^

A lot of the BMW M3 E46 crowd swear by the 10/60 German Castrol as a regular use pour, but I just can't see it as absolutely necessary unless the thing is really being beaten on and sees north of 220 oil temps regularly. That and that E46 M3 motor does like to eat for bearings. Additionally, 355 motors never have rod bearing issues as the oiling system is indeed very good so I bet sticking with a good 5/40 all day is just fine.

 

Fwiw, I use the 0w40 mobil 1 instead of 5w40 as it has more zinc to better protect the lifters and cam lobes. It's their 'euro blend' oil. The 15w50 is a racing oil so also has the higher zinc content. Different brands will be different in that aspect.

 

You might be pushing it if you plan on running her hot at a track, I don't think I would be entirely comfortable with a 40w if the car were seeing any track use, especially in hot ambient temperatures in Greece. Maybe a good 50w synthetic would be a good compromise between the two.

 

The question was about viscosity, and this is the correct question.
The answers have been stating weight/grade of the oil not its viscosity--herein lies the problem.

The best oil viscosity for your F355 is 14.5 centiStokes (cSt).
xxW-20 oil at 140dF is in the 12.7-15.5 cSt range
xxW-30 oil at 175dF is in the 12.7-15.5 cSt range
xxW-40 oil at 212dF is in the 12.7-15.5 cSt range
xxW-50 oil at 250dF is in the 12.7-15.5 cSt range
xxW-60 oil at 285dF is in the 12.7-15.5 cSt range
xxW-70 oil at 310dF is in the 12.7-15.5 cSt range

The solution is that the oil weight/grade you run is completely dependent on the temperature your car runs!

If you have an application where your oil never gets over 180dF you car will run just fine on 0W-30 oil, maybe even 0W-20 oil!
If you have an application where your oil gets up to 310dF you will be wanting a 40W-70 oil (and oil preheaters prior to starting the car.)
Most of us have an application where the oil gets up to 212dF and occasionally 245dF after a frisky back road jaunt. For this application the stock 10W-40 is just fine, assuming more timeis spent at 212 than up near 245. On the other hand if you spend more time up at 245 then 15W-50 oil would suit your application better.
Track junkies spend a lot of time up near 285dF and need the xxW-60 oils.

Oil is about temperature, Ferraris have temperature guages, Use them to your advantage.

 

Terrific post...well done Mitch