I flush mine every 6-7 k with wynns and use shell helix ultra 10-40 never had a problem used around half a litre in that time..
How long does a flush take?
No you dont drive with it in usually fast idle around 2000rpm for 15 minsthanks welly, if I poured it in before a 20 minutes drive would that be ok?
what's the problem with driving with it in guys? really?
I tend to drive into town, which warms the car up. Buy the engine flush at camberly auto factors, pour it in at the carpark there, then drive 5 miles home, and leave it ticking over whilst I get all the tools and oil drainer ready