Originally Posted by MolaKule
Originally Posted by Farnsworth
Not in my Honda manual, 10w30 is recommended always or Honda fluid which would be a version of the same. Gear oils are incorrect. Of course time marches on and what the new ones say in the manual may differ. Would have to look in the particular year manual but by and large 10w30 motor oil is correct.
As others have correctly stated 10W30 engine oil was for top-off only and was to be used only as a last ditch effort when and if the MTF is not available.
Application specific or dedicated MTFs are defined as fluids formulated specifically for manual transmissions or transaxles in which the viscosity is targeted for the amount of HP and torque to be transferred and which has special FM additives for synchronizers and for shifting in wide temperature ranges, so MTF is not just gear oil.
The first dedicated MTFs made specifically for synchronized transmissions was the Texaco formulated GM/ACDelco Synchromesh fluid at 10.0 cst at 100C. and until recently, 10 cSt was the major fluid viscosity. As higher mpg ratings were sought, the fluids specified were reduced in viscosity to 7.5 cSt and then down to LV viscosities of around 6.0 cSt.
There are many resources on BITOG that can help one understand the differences in lubricants such as:
Manual Transmissions and Lubricants
Good info thanks for the link.I try to make sure my opinions are from experiences, and I am somewhat perfectionist about following specs in the manual, even 30 or more years ago. You're way past me in knowledge about oil, I have to stick to what I remember and it's what I said.