Originally Posted By: KD0AXS
It's really impossible to make an actual recommendation without knowing the application.
Exactly.
That said there probably aren't any 5W-50s that are actually "good", they are all very shear prone with the possible exception of RL 5W-50. Not that that that necessarily is an issue again depending on the application. The grade also has a very large range of virgin viscosities ranging from HTHSV 4.0cP to 5.0cP if not higher.
BTW, there is only one 5W-50 grade on the Porsche A40 list of approved oils and that is M1 5W-50 which is also shear prone but it is heavier than the spec' M1 0W-40 if you need something heavier in whole or part (as you can blend them).
And likely the main point to be aware of is that of the few modern specialty applications that spec' the grade probably none actually require an oil that heavy for normal street use and will run better on something lighter.