This is not my idea but rather one I just found on a Youtube video. Happened across a video of this guy detailing an engine and followed up by looking at his other videos. Looks fairly easy to do with an airbrush.....and a very good eye for detail. a pretty nifty tactic in my book.
(https://live.staticflickr.com/65535/51693480480_9c4067f431_m.jpg) (https://flic.kr/p/2mKYALQ)exheat2 (https://flic.kr/p/2mKYALQ) by Nathan Pitts (https://www.flickr.com/photos/193115025@N07/), on Flickr
Photo is a bit cloudy as it is a screen grab off of a video rather that a still pic. But you can see the idea. Scroll to about the 6 min mark in this vid and you can see the process he uses plus better views of the result.
https://www.youtube.com/watch?v=ew4NP1Uu004&ab_channel=ScaledDownCustoms