Originally Posted by JamesHealey

Good place to start on most cars is about

60k in the rear, 300k in the front.

The heavier oils in the front make the car easy to drive, and the lighter oils in the rear make the rear stick..

You can go too heavy on the front and it starts to act like a spool (maybe you want that?) and you can go too light on the rear and it starts to diff out.

If you run too heavy on the rear say like 100k it's going to have a LOT of steering and be hard to drive.

40k-80k is normal for the rear
100k-500k is normal for the front

experiment and speak to local drivers who run on the same tracks as you.