Sorry Critic, but I believe that threads would have better answers if more details are included in the question. Year/make/model/engine/transmission gear count/transmission type/AWD/RWD/FWD/.... should be MANDATORY to help keep the forum 'to the point'. And, with the lack of a good edit button, just making sure it wasn't a 300 or 350. Also, when someone mentions a vehicle, the entire platform and previous/future version come into mind.
Maybe I think too much but, Rx330 to me means Es/Camry/avalon/solara/highlander/400h and similar engineering from any/every Toyota/lexus that I've ever working on...... More info is better then lack of info.
I was also stumped on why someone would remove fluid without knowing how to refill it? I was trying to be polite instead of just answering with "Use the #@$%! dipstick".
Typical Toyota ATF fluid check is hot, on a level surface, with vehicle running in park. As mentioned, just about any company that provides a UOA for oil should be able to test the ATF.
Also, if you remove 3.8 quarts, it would be really easy just to add back the 3.8 quarts and not worry about it. Most transmission have a running range. It won't care if it is a couple ounces too high or low. This helps make up for incorrect ATF temp and checking on a not so level surface. If you bought 4 quarts, use it all and call it a day. Your northern location, on average is cooler, so you might benefit from a little extra ATF.
I like the suction method of fluid removal. It is usually easier and sometimes less messy then drainplugs. Servicing a car from the top is easier then crawling under it, less chance of ruining your concrete driveway, and less likely to have leaks caused by loose drainplugs.
KBFXDLI, since you are now an experienced fluid extractor man, consider changing that ATF more frequently. Once every 6-9 months would help extend the life of that transmission. As mentioned above, you are only servicing half the fluid. Make up for the 1/2 fluid service by performing it more frequently.
Another thing, why does the owners manual tells you to visit the dealer when the vehicle is already equipped with a dipstick? could it be that someone screwed up on the owners manual, could it be that dealer will measure temp to make sure level is perfect, could it be that the dipstick was to be phased out but slipped by for another couple years, could it be an easy way to sell a full ATF flush at the Lex dealer, could it be that Lexus assumes the typical owners is over educated ad doesn't have the common sense to read the dipstick.....