Well have 2 Toyotas and 1 Lexus ES350. The ES is coming up on 50k and I want to exchange the ATF. Took it to the dealer and they won't do it and recommend it only be "checked" at 100k as "the new WS fluid doesn't break down like the T-IV" They said they cannot use their BG machine as the chemicals are not compatible with WS. I wish they had just told me over the phone versus after I brought the car in. Since there is no dipstick and only a fill and drain bolt I am inclined to just do drain fills on my own. Starting now and every 20k for the balance of the life of the car. I did read a post on here about it but can't find it. I am wondering if I should just drain cold and measure the old fluid and replace with the exact same volume OR follow the manual using my IR thermometer and drain-fill (over fill 1/2 qt) heat up the trans to 115F and pull the plug on the fluid level measurement tube. Has anyone done this and how well did it work?