Rear diff and manual trans fluid

[thisismatt]

I think the problem you're going to have is nobody staffing their "customer service" has any involvement in the industry at all, they're probably just farmed out CSR's. They can read labels and that's about it.

[HRH]

You may be right, and if I get another keyword response letter, I'll find an 800 number and bitch at someone. I'm a manager, I'm good at being an asshole. :D And with the number of morons this season who don't understand a 36 dollar set of cables will break if you stand on the gas, I'm okay to give a little back.

 

Seriously, all day long: "These cables broke, I want my money back." Fing 'tards.

[thisismatt]

Broken cables? Tow strap?

[HRH]

Sorry, we're all out of tow straps. :) And then today, I thought I should buy a snowblower and then it hit me like oh yeah, they're all gone too!

[thegreencar]

*Bumping this thread back from the dead.*

 

Having the itch to work on the car today I thought, why not change the trans and differential fluids. As far as I know, they haven't been replaced in the last 15 years(i just inherited the car). So i went through the threads on here and the 510 Realm, and followed the vaious links. I read about the possibility of damage resulting from using GL-5 in the transmission, so I was sure to take notes before I headed to O'reily, (the local independent store was closed) When I got there everything was GL-5, except for 140w GL-4 and a O'reily store brand 75/90 GL-5 that said it was safe for GL-2,3,4 and MT-1 .

So my question is, can an oil really be that backwards compatible, while not harmful to older components? I am ususually trusting of store brands, but still they aren't the ones that will have to rebuild the whole thing if it blows up.

Thanks,
Michael

[datzenmike]

GL-4 contains about 4% of a sulphur compound that coats the gear tooth metal and provides a scuff resistant surface. In addition to the steel gears there are copper alloys such as the bronze synchro rings that are attacked by too high a concentration of sulphur in the oil. The sulphur bonds to the top molecules of the copper but are easily cracked and broken off like old paint by wear taking the protective film with it. The sulphur re-plates itself on and is worn away over and over and the synchros slowly erode away. Transmission gears transmit rotational motion, are cut differently and GL-4 is more than enough protection if changed every 3-5 years.

 

GL-5 contains about 6% of these sulphur anti scuff additives and provide extreme protection from metal scuffing on differential gears that transmit motion through 90 degrees and are a totally different cut of gear. There are no copper alloys in a differential.

 

Hey 2% isn't much of a big deal, right? Think again. The difference between 4 and 6 is 2 or 50% more. Yes GL5 is far superior to GL4 for scuff protection... BUT not good for copper. If looking for transmission oils it has to be GL-4 or... 'marked copper or yellow metal safe'.

[thegreencar]

Thanks for the info, that was just what i was looking for. I played it safe and got some GL-5 for the dif, but I'll get some gl-4 tomorrow.

 When I drained the differential the oil was dark but still translucient, not black or very thick. amd there wasn't very much metal stuck to the magnet on the plug. I'm taking this as a sign that this little gal is a pretty tough broad.

[DatsuNissanLove]

Just for the record... with a lil help from draker..NAPA carries sta-lube gear oil and is api/GL4.. part# SL24239.. for trannys.. and GL5 you can find pretty much anywhere...

[datzenmike]

Thanks for the info, that was just what i was looking for. I played it safe and got some GL-5 for the dif, but I'll get some gl-4 tomorrow.

 

 When I drained the differential the oil was dark but still translucient, not black or very thick. amd there wasn't very much metal stuck to the magnet on the plug. I'm taking this as a sign that this little gal is a pretty tough broad.

 

The oil shouldn't darken unless something gets in and should be clear golden, generally. Oil does not last forever though. It gets hot and cools the gears by transferring the heat around by splashing on the case. It should be changed every 30K miles. That's at most, $3-$5 a year