Changed gearbox oil - did I fill it enough?

[autojack]

The first to second gear shift in my car has always been tough when it's cold, ever since I got it about a year ago. Once it is warm, it's generally easier. Other shifts are always OK. I have maintenance records going back to 2007, and the only record of a trans oil change I found was from 2009, 20k miles ago. So I decided to change it myself, and then I would know what was in it and when it was done. This is a 1988, so G50 gearbox, no LSD. I went with the Redline 75W90 NS MTF fluid from Pelican.

I took it for a ten minute drive, and then put the car up on jack stands and did my best to level it using a bubble level, but it was still showing a little high toward the rear. Not bad though, so I went ahead and opened the fill plug. I was surprised to get gear oil pouring out from there! Thinking it must be more sensitive to leveling than I realized, I put the plug back in and lowered the rear 2-3" more (measured by the jack stands on the jack points in front of the rear wheels). Even then I still had a trickle coming out the fill plug, but I figured I would start with that. All told I would say I drained half a pint from the fill hole, including that initial gush before I put the fill plug back. I drained the rest, and noted only minimal metal shavings on the drain plug magnet. No chunks or anything. The old oil was dark blue, and the Redline is light brown, so it must have been something different in there before.

The Bentley manual says the G50 without oil cooler takes 3.0L of oil. The hand pump I bought from Pelican says it moves 1oz per pump, so doing the math that should be 101 pumps. Having drained the gearbox completely, I started pumping. At times the pump sucked in air and I had to squeeze and angle the 1 gallon jug to get it going again. In the end I counted 106 pumps before oil ran back out.

So after all that, it *seems* like I've filled it enough, but I get paranoid about these things when it's my first attempt. Would any of you have any concerns about this approach, or am I all good? Thanks in advance...

[pmax]

Unless you spilled a liter or more on the floor, I don't see how you could have underfilled.

I filled until oil started overflowing out of the fill hole. Pretty much emptied the gallon of Delvac with just some left in the plastic tube. Still haven't identified what oil was in there before. It was also dark bluish.

Is Redline 75W90 NS MTF better than the Delvac ?

[gamin]

Blue was probably Swepco.
Should use synthetic in the G50.
Shift to second on my 88 is as you describe, tight until warm. New oil. Friend with 89 has the same experience. One might conclude that it is normal (?).

[gamin]

Always Delvac in my 88 G50. Never a problem but that would probably be the case if I were using Redline.

[Jesse16]

Regarding filling, I'd say I'm surprised you got as much as 1 pint from the fill hole but I wouldn't be concerned and its late for that anyway. The gearbox has to be vented so if someone managed to stuff in extra oil it would have been making a mess and blowing out somehow before.
As long as your car sits on a reasonably level surface, just fill as myriad threads describe and pay little attention to how much goes in other than knowing its gonna take the specified amount approximately. When oil reachs the fill hole it will start dribbling out so stop adding. Let it dribble a little, wipe off the hole and replace the fill plug. I use Brad Penn Hypoid Synthetic 75-90, seems fine. Needs to be Hypoid oil, Porsche says GL-5 and the usual temp info. on weights.

[autojack]

Thanks guys, I won't worry about the level then. I won't be shocked if the second gear shift is still a little stiff first thing, that was only part of the reason for changing it.

As for the oil choice, I researched it on the forum, and this post in particular from Matt Monson convinced me to try something other than Delvac:

Transmission fluid for 89 g50 carrera

He says he only recommends it for track use, and any of the other oils discussed are fine for daily driving. Given that Pelican sells Redline and it meets the technical requirements, I just went with it.

[Fast Freddy 944]

Stick your finger in the hole, and tip it down slightly, pull it out, if you have gear oil on the tip, you are successful! There you go sport!

[gptom]

I have always pumped in oil, then let it sit for 30 min an add to fill plug. Thinking here is that cold gear oil needs time to flow over gears etc & settle

[pmax]

Originally Posted by gptom

I have always pumped in oil, then let it sit for 30 min an add to fill plug. Thinking here is that cold gear oil needs time to flow over gears etc & settle

Good point. In my case, I poured the oil down an 8ft hose and it took half an hour just to empty the container so should be fine I believe.

About the oil, based on one test drive, cold shifting seems better than the dark bluish stuff (Swepco ?) but that could be due to the warmer weather so who knows.

Here's a fun read.
Swepco Transmission Fluid Question

[jamesrg]

If you think trying to pick a fluid for the G50 w/o a LSD was fun, I went thru a few hundred posts before I settled on something. I have a LSD in my G50. Still not sure I have the right stuff, but gonna give it a try in the next week. Just put a bottle BGK 44 in the tank before my oil and trans fluid change so I have to run that thru it first.

[manbridge 74]

Yeah you want to check it after some time or short drive. By the time the GT2 came along there were about four chambers that were connected by small openings. Takes time for it to reach a level.

[autojack]

First long drive since the change today, shifts are noticeably better when cold. Not astounding night and day difference, but better. I won't bother to guess how much is down to different oil versus just new oil. I'm just happy I got it done.