be consistent in your oil level reading technique. You can be down a quart of oil without entering the engine damaging zone, so small differences in how you read oil won't make a difference, just be consistent. I have yet to add a drop of oil to my Si in 11 months of ownership and a lot of miles on her. I bought a spare quart of oil when I got the car to use for topping up purposes but it just never needs it. It may take a few years to go through that quart if things stay the same.

 

Oil expands and become more viscous under high temperature, checking your oil before your commute on a level surface is ideal.

Cold weather will affect the reading but much less than checking it after continuous use.

 

Check it in the morning. Don't over think it.

 

If you check it cold in the morning pull out the dipstick and wipe it off and reinsert it, then take the proper reading. If you try to read the dipstick upon first removal the level could be artificially high, so remove , wipe, reinsert, remove and read.

 

This^

But also waiting more than 3 minutes won't make your reading inaccurate, just means everything has cooled off and settled more

 

Longer is more accurate.

Most oil will flow and settle to the bottom very quickly after shutting off the motor, but the longer you wait, more will settle.

It's diminishing returns though.
Maybe 1 min is 95%
Maybe 2 mins us 99%
Maybe 3 mins is 99.5%

Im just throwing out numbers, but the last little bit doesn't make much difference. It makes more difference if you're parked on a slope.