I really enjoyed reading this Thread, we have a member who wants to heat some roller bearings in Synthetic 10W-30 motor oil. From reading the title, I am guessing he already has a quart of Mobil 1 10W-30 Synthetic Oil. He is asking about the safest max temp before ignition.
Tim Vipond, the Amsoil Salesman, does not even answer the OP's question, he puts up an Amsoil Link, breaking Forum Rules.
JMorgan, who is a Schaeffer's Rep, actually answered the OP's question, and he did not even put up a Schaeffer's Link, he did not try and sell him Schaeffer's Oil.
The OP thanks JMorgan