Slightly lower idle after oil change

[schoward]

Recently changed oil like I always do replacing shell 15/40 rotella with same. Filled it kind of hastily but did not appear to overfill. I dumped the oil in kind of fast (as fast as funnel could take it) but level seems perfect as always. Stick level ok and gauge is about 3/4 when warmed up.

Old oil had about 2-3k miles on it.

Car runs fine but idle seems slightest bit lazier now especially in the warm up range. Cold ok and hot pretty normal. Have done this many times and seems weird this time. New oil has about 100 miles on it.

Any experiences like this or ideas?

[Walter_Middie]

Did you bump something and create a small vacuum leak? Old vacuum lines disturbed? Oil tank vent line?

[Marc Bixen]

Check and see if the oil cap seal fell out, or the cap isn’t on correctly. RPM should drop slightly with the cap off.

[schoward]

All -Thanks for the ideas - Cap seems fine and idle drops when remove it and did some carb cleaner spray and check for vacuum leaks (and on injector seals also which are only 3 yrs old). All seems fine. I changed the plugs as they had not been done in a long time and checked the mixture. One plug on #2 had slightly more deposits than the others but generally better than I expected after 8 years.

Car starts and drives pretty well but idle is lazy and a little lumpy. Once fully hot it smoothes out a bit but something is off.

Important - I am getting an oily odor and light smoke emanating from the Fan when car warms up and is running and then also after shut down. It smells different.
Smelly smoke from internal cavity behind the fan.... This is not normal for the car.

That help generate any new ideas? As described above, main change was I changed the oil kind of hastily dumping the full pour of oil (10 QTS) in in one shot. Oil level is fine though. Is it possible I overfilled and it burped some excess somewhere before it circulated now giving me a normal oil level? Any suggestions on how to remedy?

Possible something with oil breather hose is a factor here or something else unrelated to oil change?

Thanks.