




Not sure of your location, but I used Shell Rotella 15w40 for many years.
In the summers of TN we have high 80s and 90s F, but not quite consistent 100F/40C
I do not see 25w-40 oil around here - but I think that is geared more towards sterndrives, outboards, or 4 strokes.
Since you probably have a 325 (GM 350 block), I would probably look for another option - but not sure what is available for you based on where you live.
2018 Supra SL400