I just bought a very clean '01 Jaguar S-Type 4.0L v-8 with sport package and navigation system as a suprise for my wife. It has 30K miles and is still under warranty. I was looking at the owners manual and it has a really confusing chart (must be the british english ) that lists the following as acceptable oils: 0W30 5W30 0W40 5W40 must meet spec. ILSA GF-2 Then it says that 5W30 is preferred but 10W30 or 10W40 is acceptable in moderate to hot climates. Jag recommends oil changes every 10K (which is included in the warranty). The last owner had the oil changed every 5K. The dealer uses 5W30 dino oil. That seems like a long interval for 5W30 dino oil in a v-8. Looking at my current stash I'm considering one of the following for long term use: 0W30 Castrol GC 5W30, 10W30, 10W40 Chevron Supreme/Havoline 5W40 Mobil 1 Truck/SUV I'll probably do an AutoRx flush with Chevron and then start using one of the above. Any comments on what to use and tell me why you picked your choice. Any Jag experts out there?