My 406 is got about 9,000 miles on it since a rebuild. Is this a good time to change to synthetic or should i stay with the conventional oil? thanks.

The perfect time. Go for it!!! I suggest Mobil1. Cheapest alternative and readily available on sale at Wal Mart. Just good stuff. Change every 5,000-10,000 miles or so, depending on the beating you give her. I also suggest a Fram HP4 filer, or other small-micron filter alternative. Again, Fram HP4's are easy to come by and never more than $8 each. You'll have better oil and fewer damaging particles, too. Cannot beat that!!!

My motors have all run way past 200,000 miles on synthetic oil.It's definetely worth the money.
Mobil 1 is available everywhere.
I also run synthetic trans fluid and rear end gear oil.
After seeing the insides of my high mileage motors, even my cheap friends are converting to synthetic.
-Rich-

Are the Fram HP4's biult better than their other filters? I've seen the inside of a Fram filter and it looks like I could do a better job with an empty toilet paper roll.

It depends. How many miles can you run before the engine oil gets contaminated? I use to run mobil1 until I found my driving habbits were bad on oil and I could only run about 800 miles before the oil was contaminated by fuel. If I were you I would do this. Change to synthetic and keep and eye on it. Find a local place that tests oil like a heavy industry retailer (Cat dealer) and have them check your oil in between normal oil change intervels. They sell a test kit for $10 and send the sample to a lab for real results. They can even tell you if your burring up rings and bearings just by looking at the oil. This is the only way to find out if synthetic is right for you.
SSC