I used to use Jack with an L4 and found the following:

On first application grip would be great from the off but go loose at about the 6:30 mark.

On 2nd application tyes would be loose for 2 - 3 laps, then work fine till about the 6 min mark then be really off.

Never used they same tyres more than 2x a day...

I changed to CS-Grip (from Schumacher) and the car is good for the whole run.