Originally Posted by ep10
How often do I need to use the tire sauce?
This depends mostly on the grip level of the track.
For example, indoors with foam, I use 40 shore tyres (hard) and only apply additive for the first round of qualifying. The reason for this is the grip comes up through the evenings racing, so applying any more additive usually results in a car that is too twitchy, or even worse, grip rolls.
Although for example, outdoors on rubber you may need additive on for every race, because grip levels are low. (cold/wet track, or rain has washed away all the grip the track had previously).