Dumb Question...but

I changed the oil today from the Ursa 10W-30 that I had used in winter to a 15W-40 Mobil Delvac 1300. The engine doesn't seem to idle as high as it did before. This is good...its a quieter, more diesely idle. Is it my imagination, or could there be something to this?

I know it's a dumb question, but what the hell.

Maybe it isn't your imagination, but it is highly unlikely due to the oil change. Moving to a universal grade oil like Delvac is a good move.

Have a great day,

Ursa was a universal grade (used in Europe extensively) but was rather light.