Delo 15w40 in the summer?

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Feb 6, 2021
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Massachusetts
I'm currently using castrol edge 0w40, however delo is pretty cheap, frequently goes on sale around here, and I dump my oil once a month at 4-5k so no chance of it staying in the sump into the fall or winter. Any reason delo would be a bad idea? My engine does not seem to care what viscosity I dump on it, if anything it runs better with less racket on the 0w40 and I still get 30-35mpg mixed.
 
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I've used Delvac 1300 and NAPA All Fleet in older engines in summer and fall even. I had a 94 Jetta I ran it in, and a 94 Sentra. In the Jetta I ran 5w40 in winter and spring, but I didn't really notice any running difference between the two.

I don't have much more to add beyond that it didn't cause me problems.

Of note, some 15w40s actually have viscosity similar to 10w40s now. I think the Delvac and NAPA All Fleet according to PQIA were thinner than Castrol GTX 10w40. With the Sentra on Supertech 10w40 in winter (below 32F temps) I had zero start problems but you could feel it was a bit sluggish until the car got hotter vs having 5w30. I think Delvac is rated for a colder pour point than some other 15w40 oils, too, iirc.
 
Yes my brother, come join us here in the 15W40 thread

 
15w-40 oils can be used down to around 3 degrees F. How cold does it get in summer by you? :)

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Yes my brother, come join us here in the 15W40 thread

Yes by all means.

You are already using a 40 grade so no worries at all.
 
I used to use 15W-40 Chevron Delo in my 4-cylinder Mercedes C230, the '97 W202. The owner's manual had a temp chart like the one in post 4. Never did temps get cold enough to test the oil's effect on starting, and the oil certainly handled the endless wearying hot weather without issue.
 
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