Oats have a bitter enzyme that must be neutralized. The method used is by heating the Oats and the internal moisture will steam & neutralize the bitter enzyme. By the Gluten Free Matzos made from Oats, they are heated on trays in a tunnel oven. They are heated to 250 F +- for ten minutes. The process may cause the oats not to be acceptable for pesach matzos-Talk to a knowledgeable Posek.
Note: The Lakewood matzah bakery says their oats are not heated at all. It may be that they are just unaware. Based on our information, it's heated as stated above.
May one use Matzos that went into into the oven approx. 22 minutes after the water was poured into the flour. Some claim that they count the "18 minutes" from when it gets worked into a dough, which is actually 22 minutes. All for the unsuspecting yeshiva leit.
The only recommended machine matzah is the Beit shemesh chaburah machine with only Bdatz She'airis yisroel.
Others claim that there is a written teshuva on this issue, but they don't want to give it out.
Reb Chaim Shmulevitz, Z"L writes by Mechiras Yosef, a psak that can't be publicized is "botul" and has no halachic validity. So there is no written teshuva per se.
Normal process at an Israeli facility that produces machine matzos is to stop & dismantle & clean the machines every 18 minutes. Normal clean-up & dismantle take 25-35 minutes, an expensive procedure. In order to economize and give Lakewood Yeshiva leit an affordable machine matzo, the matzoh bakery was instructed to dismantle, etc only once an hour, thereby bring down the cost per hour, hence they could sell the matzos for less to the unsuspecting yeshiva leit. Are they still calling it 18 minute, or mehudar?