I have a 2005 Chevy Silverado 1500 2WD with the 4.3 and four speed auto. I remember reading somewhere(probably on here)that you cannot coast in neutral with some autos. I was wondering if anyone knows if I can pop it in neutral and coast down hills. Thanks!
You can't coast in neutral with the engine off. You can with the engine on with most automatics.
Some transmissions aren't so great for it and you know because they heat up (triggering a check transmission light, or on your truck a message on the info center combined with a limp-home program) or react weirdly (bucking or RPM jumping around when you shift). Your transmission is almost certainly the 4L60E and is great for it.
I've been doing it for a long time with my 2002 GMC Sierra 1500 4x4 5.3 4L60E. It's a particularly good automatic transmission for engine-on neutral coasting.
If you want, rev-match before putting it back in D. Predict the RPM it will be at in D and rev it up to that RPM before shifting to D. It's not necessary but it's nice for feeling comfortable about doing new things with your same old transmission.
So the year I spent coasting my kei-car in Japan with the engine off for 3 miles at a time was BAD for the tranny? WHOOPS!
I neutral coast my Corolla, but have found that usually turning the O/D off when coming up to an eventual stop actually saves more fuel. My SGII shows that the fuel cutoff will kick in down to 40mph w/OD on, and down to about 33mph w/OD off.