While reading about switching from regular to synthetic oil on this messageboard, a few people have mentioned that you need to completely flush the old oil out of the engine before you put synthetic oil in. What is the correct procedure for doing this? I've never read anything about the procedure prior to this.
Thanks.

 

That is not necessary. Synthetic will mix acceptably with any kind of dino juice, without the nasty effects that different kinds of the old stuff used to create.

However, it is usually higher detergent than mieral oil, and will tend to dislodge and dissolve deposits of crud that have long laid in the recesses of your motor.

I'd suggest putting a quart of ATF in your existing oil whenever it gets low, then running that for 1000 miles or so, then doing the swap. That way you won't have to change your new expensive oil quite as soon as you would have if you let it be the first strong detergent to eat the schmutz out of there.