I switched over to the MOBIL 1 synthetic about 3 years ago with my 2000TL.
I purchased my car new in late 1999 & had the oil changed on a regular basis. I had the regular oil put in at dealership about every 4,000 miles or at the pakage dealer service intervals. When I swithed to the MOBIL 1 I notice the ease of starting the car on winter mournings. Not to say that I had problems with starting with the regular oil but it started better with the synthetic. The service advisor told me at the dealership when I first changed over to the MOBIL 1 that the HONDA oil filter should be used to avoid problems. This was a bunch of crap but he might have heard somthing about some of the bargin priced oil filters causing prolems. I use the Mobil 1 high quality filter The car to me runs better with the synthetic oil. The oil change I got last summer I just had that changed a few moths ago. MOBIL 1 came out with the EXTENDED PERFORMACE 15,000 mile oil last year. They say the oil is good for 15,000 miles or one year. I won't go the 15,000 miles on it but I did about 10,000 miles with it. I do mostly highway driving so don't need to change oil that often. The last oil change a few months ago I also had the newer MOBIL 1 EXTENDED PERFOMACE oil filter put on. I had been using the older MOBIL 1 filters. Synthetic oils are 700 times greater then conventional motor oils. This is a factor called sher strength. You can change to synthetic oil at anytime no matter if the car is old or new. The only time you would not change to synthetic is if the car is already leaking oil or it burns oil. Synthetic oils will not cause leaks 85% to 95% of engine wear happens at start-up. I learned some of this in a Maint.Sem for Car Owners/Mech that I took a few years ago.
2000 3.2TL NIGHTHAWK BLACK PEARL/EBONY W/NAV
OEM Body Kit/ Rear Wing Spoiler/Roof Visor
OEM 16-inch optional Chrome Muilt Spoke Wheels
OEM Gold Emblem Kit/ Black Fenderwell Trim
OEM Trunk Tray /Upgraded 2001 Cup Holder Insert
OEM 6 Disc Trunk Mounted CD Changer
Pioneer GEX-FM903XM Univeral XM Digital Tuner
All Weather Floor Mats/45%Tint sides 50%Rear