Toyota Repair: transmission fluid, transmission failure, mercon

Question
Ted--

I just had the 60k maintanance done on my 2005 Sienna, and asked that the
trans. fluid and filter be changed. I gave written instructions to use Toyota
ATF Type T-IV fluid, as specified in my owner's manual, but they used "ATF
Dexrtron III Mercon Pro," plus "Lube Guard Friction Mod" as an additive, which
my mechanic said makes it the same as the Type T-IV. He's a good mechanic,
but I'm a little uneasy with the switch. What's your opinion?

One more quick tranny-related question. Upon first start-up in the morning,
the engine revs to 1500 RPM for awhile. This seems too fast, and I worry that
shifting into reverse at that idle speed stresses the transmission. Your
opinion?

Thanks!  --Jeff

Answer
Toyota does not recommend using dexron III, I can only go by what toyota recommends which is typeIV fluid, using other fluids may cause erratic shifting,harsh shifting and possible transmission failure. I don't know whether adding the additive makes it the same as typeIV, I'm not familiar with this additive so I can't say. The fast idle speed of 1500 rpm is normal.