sup s2ki fam,

I just did the first manual transmission/differential fluid change on my car a few weeks ago (since new ownership).

Upon removal of the MT fill plug, I noticed that is was ~0.5 qt overfilled. The diff was low.

When I pumped in the fresh fluid, I let the excess flow till it started dripping.

Recently, I have been enjoying my current s2000 in the canyons, and plan to track before 2013 is up.

Due to these conditions, the thought of "adding just a little more fluid for more protection" keeps invading my mind.

Based on the above context, what would you do?

How much do you fill? Do you do a "slight" overfill, or do you let it drip?

Thanks in advance! peace

 

With the car level, fill until it starts dripping back out the fill hole. When it stops dripping, close the fill hole with the plug and fresh crush washer.

I'm not aware of any good things that can happen by overfilling this equipment, only bad things.

Remember that these fluids expand as they heat up. If you are already overfilled, you can expect aeration bubbles to form and poor lubricant performance and/or seal leaks to develop from over pressurizing the system.


Some manufacturers tell you to fill 1/4 to 1/2" below the fill hole, then drive the vehicle to heat up the diff fluid, then pull the fill plug to drain any excess fluid with it at operating temp.

 

The capacity is 0.8 quarts. I typically get just under a quart in before it starts dripping, so seems about right

 

once my car is as level as i can get it, i pump, wait for it it and then fight my oily fingers to get the plug back in. usually its still running when i get the plug started. There is about an inch of fluid in the bottle still and a punch on my hand.

 

I can't work under the car when its level.....

The diff has a breather so it can not really build-up pressure by expanding oil.

It's much more important to use the right fluid

 

I tend to force a little more in than just a drip. If the diff takes .8 of a quart and you use a whole quart I highly doubt the extra .2 of a quart will harm the differential. Especially with the breather valve to relieve any excess pressure. I use the AMSOIL 75w90 and I love the stuff...