XRAY - Model racing cars

+ Is it right that lighter shock oil is meant for lower grip tracks and heavier oil is meant for high grip circuits?

+ What is the recommended oil for low grip and what is recommended for high grip?

+ Does a lighter oil handle bumps better and also heat the tyres up quicker?

All sounds correct to me. Outdoors in the UK I run 30wt as my 'standard' oil, and go to 25wt in the winter when the grip is low, or 35wt in the summer if its hot or if the grip is high. Part of this is just compensating for the properties of the oil (it will thin out as temperatures go up), part of it is adapting to the grip available.

I find thinner oil makes the car more agressive and gives more overall steering. Thicker oil calms it down and reduces chance of grip roll (rarely an issue outdoors).

I'm not sure the oil makes a huge difference to the tyre temps. When the track is hot in the summer the tyres overheat regardless of car setup. Sorex32s are good up to about 40deg tyre temp. When the track is 45-50deg it's impossible to get the tyres into their decent working window. Maybe if it's borderline you can knock a couple of degrees off by using thicker oil and softer springs.