I run Delvac 1 5w40 in my old diesels and it seems to work great, I would think the gas engines of similer vintage would like it as well. According to my 603's owners manual 5w40 is recomended for just about all temps.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200