Can we use engine oil as a substitute for manual transmission fluid, say 75W90 API GL-4?

No. That's why I asked.

I am exploring the possibilities.

There are people who don't follow the car manual.

Does your car manual says that your engine must use fully synthetic oil?

Back to my question....

Can we use engine oil as a substitute for manual transmission fluid, say 75W90 API GL-4?

http://www.cb7tuner.com/vbb/showthread.php?t=176856

Did you even bother to read this?

http://www.cb7tuner.com/vbb/showthread.php?t=176856

Using the appropriate engine oil of the correct viscosity (typically 5W30 or 10W30) is not as bad as using the wrong API GLx manual transmission fluid.

I quote here an extract of Wikipedia......

"Most lubricants for manual gearboxes and differentials are hypoid gear oils. These contain extreme pressure (EP) additives and antiwear additives to cope with the sliding action of hypoid bevel gears.

EP additives which contain phosphorous/sulfurous compounds are corrosive to yellow metals such as the copper and/or brass used in bushings and synchronizers; the GL1 class of gear oils does not contain any EP additives and thus finds use in applications which contain parts made of yellow metals.

GL-5 is not necessarily backward-compatible in synchro-mesh transmissions which are designed for a GL-4 oil: GL-5 has a lower coefficient of friction due to the higher concentration of EP additives over GL-4, and thus synchros can not engage as effectively. Also, transmissions which explicitly call for GL-4 oil may have been designed around this lower concentration of EP additives and thus may contain yellow metal parts which GL-5 will corrode."

http://en.wikipedia.org/wiki/Gear_oil

Would you use 5W30 viscosity oil if your manual says to use 10W30?

My car manual says to use 2.15 litres of genuine MTF with specification 75W90 API GL-4.

What brand and part number of MTF is suitable to use as replacement as I don't know what the previous owner used.

It is about time to change the MTF.

Thanks!

I shall take 3 litres of Redline MT90 then.

Are you sure it is API GL-4 certified and not a GL-5?

I don't want the brass synchros in my MT to be damaged by the excessive sulphur/phosphorous EP additives in a GL-5 spec-ed fluid.

I can't even find a bottle of MTF at the Shell and Petronas stations near my place, don't say whether the specs are correct first.

My manufacturer/brand own fluid is Hyundai Genuine.

Don't tell me I have to go back to an authorised service centre for a simple change of MTF.

No need to spoonfeed.

I can do it myself.

I just went to the petrol stations this morning to find the MTF.

None available.

I placed an order for 3 bottles of Redline MT-85 (75W85 API GL-4) at RM55 per bottle already.