DNxHD

If I create a video in Davinci Resolve 17.1 and use the codec(DNxHD) will it be encoded without any quality loss. In Resolve I am only color correcting the video. I will import it into Adobe Premiere 15 for further processing.

You want to use DNxHR which is a newer version of the codec.
It is visually lossless and suitable for your objective if you use the HQ or HQX presets. HQ supports 8 bit color while HQX supports 12 bit.

Adobe Premiere 15 will not import DNxHR. It will import DNxHD. The videos appear to be lossless.

Adobe Premiere 15 will not import DNxHR. It will import DNxHD. The videos appear to be lossless.

Premiere supports DNxHR. Though there is a bug being reported that file exported from Resolve 17 is flagged incorrectly making it unreadable in Premiere.

Try an MXF wrapper.

Is DNxHD Lossless?

Is DNxHD Lossless?

It's technically not lossless but you can consider it "visually lossless". The same applies to Apple Prores codecs.

Or to Cineform and Grass Valley.

The GoPro Cineform appears to be lossless when I import the video into Premiere. I export the video from Premiere to H.264. I do not see any video quality lose.

Yes "Appears" is the key word.... but it's not lossless.... but it's a great codec, it's wavelet based which is a little different than most other codecs.... do a Google for info on it.
Even in the low compression settings for it it works very good.....you can smash it a lot on the higher settings like Film 1 or 2 and it holds up well for multiple processing.
To truly get lossless you'll need to go uncompressed but then your talking about very large file sizes especially at 4K and beyond.

I shoot for a company that edits with Premiere Pro. I shoot RAW, apply a basic grade to Rec.709, and render out Cineform AVI files at Medium quality.

The file sizes are quite reasonable and the quality is excellent.