How do I change gear oil?

[Daedalus]

Ok, I bought 4 quarts of Redling MTL and I want to change my gear oil soon. A while back I had found a how-to online, but I cannot find it anymore. Does anyone know how I can do this? I am pretty sure that I know what I am doing, but I do not want to screw anything up. This is what I "think" I know.

I will need a 17mm hex head.
There are two 17mm hex heads on the back of the tranny. One is the drain plug, the other is the check hole.
Drain using the drain plug, fill using the ???

Thanks for the help.

[TomH]

Fill using the check hole. You'll need to use a hose to feed into the hole. Fill it to the top.

The hardest part is loosening those 17mm plugs. Most are frozen, and require heating to free. I tried unsuccessfully to get mine lose. My mechanic recommended 1 17mm socket (not an allen wrench), and a long breaker bar for leverage.

BTW: mine's an auto, and it does not have a drain plug. just a fill/check plug. So us autos have to siphon out the old stuff to replace it. What a pain in @ss. Why, why, why Ferdinand???

[Obin Robinson]

Originally posted by Daedalus:
Ok, I bought 4 quarts of Redling MTL and I want to change my gear oil soon. A while back I had found a how-to online, but I cannot find it anymore. Does anyone know how I can do this? I am pretty sure that I know what I am doing, but I do not want to screw anything up. This is what I "think" I know.

I will need a 17mm hex head.
There are two 17mm hex heads on the back of the tranny. One is the drain plug, the other is the check hole.
Drain using the drain plug, fill using the ???

Thanks for the help.

the filler hole is on TOP of the transmission. you will not see it unless you get a mirror on the end of a stick... or feel around for it. it is "capped" by a black plastic plug.

if you need a 17mm hex wrench, go to Sears, they have them for under $10... guaranteed for life too. just MAKE SURE you find the filler hole before you drain the old stuff out. also, to get all the old stuff out, let it drain for a while... like 5 or 10 minutes until the last bit of crap is out of there. i know that some places even blast compressed air through the top hole just to get all the chunky crap out. you'll see lots of metal shavings coming out with the old oil. my tranny drain plug even has a magnet in it to get these metal shavings.

good luck!

obin

[Ehab]

How often does this have to be done? and what are the dangers of not doing it?

I've had my car for 3 years, and have no clue when it was done last ...

thanks,
e

[newoldguy]

And if you haven't already done so, look for a little hand pump (at an auto supply store) that should screw into the top of your gear oil bottles. I have one for quarts and one for gallons. Feed the tube into the fill hole and pump away. Its slow going but a lot better than trying to somehow snake a line in from the top and pour it into a tube with the help of gravity.
Curtis

[Obin Robinson]

Originally posted by Ehab:
How often does this have to be done? and what are the dangers of not doing it?

I've had my car for 3 years, and have no clue when it was done last ...

thanks,
e

i'd do it fairly soon. your car will shift better, and you won't end up burning the hell out of the tranny like i did (speaking from experience here )

obin

[drews]

Did mine in the spring, some difference. I have a tip for you. Make sure the top one comes out before you open and drain the bottom one.
Mine was seized and ended up cracking the plug. That could be a real pain if I'd drained it first.

[IceShark]

For a street car change the gear lube every couple to 3 years. It makes a difference in oil selection if you have limited slip diff or regular. I have about concluded the dino oils are the best.

As mentioned, make sure you get the top plug out first before you drain the oil or you will have a big problem in resolving how to get the top plug out with a dry transmission, as in you can't drive it someplace for help. For sure use rust penetrating oil to soak the threads for an hour or two. Heat from a torch is a good idea if the plug is stuck and has never been removed in its life, which is pretty common. Just use a chunk of sheet metal as protector so you don't start something on fire from torch flame wash. Those plugs have been known to split in half, round the edges, and get real stuck under the stress of removal. So be careful from the start.

The standard plastic long and thin quart jug of gear oil will fit up into the top hole with care. Snip the end off to open, cover with your finger and shove it in real quick.

The plugs are a tapered pipe thread so when you put them back in use some teflon pipe tape and never have the stuck plug situation again.

This is a deal that can go smooth as silk or horribly wrong, if you screw up.

[This message has been edited by IceShark (edited 08-14-2001).]

[Obin Robinson]

just offhand, the spent oil SMELLS SO FREAKING HORRIBLE!!!!!!! do this in fresh air. the stench is something that cuts THROUGH you quickly. i soaked the plugs on my tranny with this stuff called "PB Blast" and let it soak for 15 minutes or so. no problems removing it then.

obin

[drews]

Just in case you do split one of the plugs, I've heard of people welding a 17mm socket into the plug, the heat from the mig torch usually provides enough thermal expansion and contraction the break the bond. Hopefully yours will never get to that point.

[mike944]

I know there is a special gear oil for cars with LSD. How do i know if i have a LSD? I'm almost positive i do. I've never had one wheel spin, even on slight acceleration during hard cornering. I know the old american cars had a metal tag on the differential that specified limited slip diff lube. Do the 944's have something similar?

Mike

[CrazySOB]

Mike,
I'm pretty sure, if you jack up the rear end of your car- spin 1 of the tires, look at the other one ( if it spins in the opposite direction- not lsd) if it turns in same direction- lsd.
Anyone please correct me if I'm wrong.


Steve

[e_nough]

obin, the filler plug is not on the top its on the side of the tranny and just above the drain hole.

the hole on the top covered with the black plastic cap is there for air expansion/contraction when the oil gets hot.

[TomH]

e_nough, that expansion/contraction vent you are talking about reminds of a service bulletin I read about automatics. It start with the following excerpt:

April 1, 1988
The following parts and procedures have been developed to reduce the chance of ATF loss from the automatic transmission housing vent. A temperature switch installed in the automatic transmission cooling circuit at the radiator closes at approximately 87~C (189~F) causing the engine cooling fans to run at maximum speed to reduce the temperature of the ATF. The cooling fans operate independently of engine coolant temperature when activated by high ATF temperature.

I have had two occasions where I found fluid dripping from my transaxle. The first time, it appeared to be gear oil, so I suspected I had a leak. Crawled under, cleaned up my transaxle, and found no signs of leaks. I took it in and the mechanic could not find a leak either.

Recently I noticed fluid dripping from the TA again, this time though it appeared to be red, indicating that it was auto trans fluid.

Now I am suspecting that I am having the types of leaks you and the service bulletin are talking about.

Both times, the leaks seemed to occur after high speed runs or on very hot days.

[Obin Robinson]

e_nough. ok, when i put the oil in my car, it went into the expansion point a lot easier than the "filler hole". i also didn't have a problem with it leaking out at all. the "filler" plug was almost siezed, and i didn't want to strip the threads.

obin

[IceShark]

To tell if you have LSD, you can do as CrazySOB says and rotate the rear wheels on jack stands.

You could also look at your option codes. Or just turn the car very sharp on a road that is gravel or has sand on it. You will hear the rear tires scratching the gravel since they will turn at the same rate but the circles you are making them follow have different diameters, hence distances to travel. So one or the other tire, maybe both, are going to have to skid.

This is why the variable differentials were invented in the first place - to cut down on tire wear caused by dragging the wheels at different rates on turns. So it isn't necessairly your drag racing that burns out the rear rubber so quick.

[Daedalus]

Are you guys sure its a 17mm hex wrench? Cuz I bought one last night and it seemed a little small. I the 17mm I had, but soon quit because i was afraid to strip the nuts.

[TomH]

It is 17mm, maybe your plug has alrady experienced some stripping/widening.

Anybody know who sells replacement dif plugs?

[AFJuvat]

Yeah, the dealer...


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