so which is the correct one to use? U mean the technician at TCM do not know wat is the correct rating for the EO to be used? I always tot using synthetic is more for convenient as u can do ur servicing every 10k...
I dont think TCM care about your FC, as long as it do no harm to the engine.
So it can be EO with higher WT. (>30)
I brought my own EO for service , 10K with Amsoil 5w30 and now on Redline 10w30.
Both serve me well, but somehow I feel Amsoil gives me better feel which I cannot describe.
Still have 8 quarts of Redline with me at home. So no plan to change to other EO from now.