White SE:
you have waited a bit long for the tranny flusher. It's supposed to be done at 30,000 miles. I have heard (note- I have NO experience with this problem) that if you wait too long, the flush will break up little pieces, but not get them all out (which, come to think of it, makes NO sense at all- that's the point of a flush, to get it ALL out) and the pieces will clog your pores. I mean, fluid channels. That's never good.
You should definitely change it, especially if it has turned a nice, brownish-black color, like a finely charred steak. That's not what you want. Also, if it smells like it's hot (that's a tough one) okay, if it smells like it's burned, GET RID OF IT.
That's my advice, change it. 66k is quite a while for a tranny with no new fluid. If yours is an auto, go have it flushed- you just can't get it all out yourself. You can try, but nothing you can do is pressurized, nor will it flush the goop out of the torque converter. It's it's a manual, do it yourself.
on the oil question, I use Mobil1 5W-30. I am thinking about 0W-30. But I am worried that it is toooo thin, and may do more harm than the added gas mileage justifies. I will probably chicken out and stay with 5-30.
But back to the topic at hand, WHY would ANYONE switch from synth to dinosaur? What advantage is there? Fifteen bucks? Hey, over 5000 miles (don't change more often unless you're just bored) that's like... three dollars for every thousand miles. You can easily save that amount by driving ECONOMICALLY once in a while (not all the time- just like, one day a week make it economical...
That's my twelve- and- a- half cents, and I am stickin' with it.
Randy