transmission Overfill what if

[240sxrunner]

I have no idea how much transmission fluid is in my car right now but i think it is low. How can i tell or can i just add a quart and if it is overfilled what will happen???

[MrFox]

if you have an auto there is a dipstick.

if you have a stick, squirt oil in until it overflows out of the fill port - the height of the fill port is the proper level.

Be sure to use a GL-4 gear lube. Don't use GL-5 else say goodbye to your syncros.

[rousie13]

Or you could just drain it and put all new gear oil in. Your transmission will love you for that one. If it's a S13 manual, the drain plug is right at the bottom of the transmission and takes a 1/4" drive? if I'm not mistaken. Then just fill it back up through where the shifter was. I know my car shifts a little smoother after I did this.

[240sxrunner]

nobody answered my question was if i over fill it ??? what will happen

[Aries]

when it gets hot it will overflow out the spill tube at the top of the transmission and smoke.Smells horrible, and smokes bad enough you thing you just blew up the car.

[240_Keyy]

what is this GL-4 and GL-5 nonsense? I put redline MT-90 in both of my transmissions and it seems to work fine...

[MrFox]

GL-4 and GL-5 are different API grades for gear oil. GL-4 is the specification for regular transmission oil. GL-5 is referred to as "Extreme Pressure"(EP) lube, and are typically used in differentials. The EP additive in GL-5 (its either moly or lead sulfide, someone correct me) is very abrasive on soft metals like syncro rings and will eat them up.

Both MT-90 and MTL are GL-4 grade lubes (saids right on the bottle), so no worries!

[Holisticbeatz]

nobody answered my question was if i over fill it ??? what will happen

transmission + over filling with transmission fluid = a big mess?

[Cyberkreig]

The excess pressure can cause leaking, especialy at the driveshaft seal.