The engine runs fine - I just want to know if this is a good oil to use in my routine maintenance of my 1972 W108 280SE 4.5L V8.

It would depend very much on where you are.

I'm in Southern California. It's pretty warm out here year round. Rarely gets below 55F... Summers get up into triple digits and dry.

Should be fine, especially in the summer. I'd probably go 15/40 in the winter.

20w50 is what I use on all of my older cars. It was the period motor oil viscosity from back in the day and worked just fine in England (where people never changed their oil).

Castrol is my preferred oil for the older cars. Mobile 1 for the E420.

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With best regards

Al

Perfect choice, all older cars, all year, southern california

Castrol 20w50 is what my Benz has in it now.
It's not what I have to replace the stuff in there. I got Castrol 10w40 to replace it.

I have no issue with the 20w50 if the starting temp is over 50 but I didn't like how slow it cranked in 40-degree weather.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k