[magician35]

'97 Sport JLX 1.8 L, 4-spd auto trans, 4X4. Does anyone have the factory recommendations for the weight of the gear oil in the differentials and the transfer case?

 

[GumbyCT]

Front & rear diff are GL5
Transfer case & tranny are GL4

 

[fordem]

Either an 80W90, a 75W85 or a 75W90 GL4 for the transmission & transfer case, depending on the climate; and a 90, 80W90 or 75W85 GL5 for the differentials.

I make one bad job and use 75W90 Mobil One full synthetic - it is a GL5, but it is safe for use in the transmission & transfer case.

 

[magician35]

Thanks. I sold my '95 Kick with the Owners Manual and the '97 Sport didn't have one. My major concern is the transfer case since we tow it 4-down in some pretty warm temperatures here in the SW. Any thoughts on regular lube vs. synthetic for the application? I'm about to do a complete drain and refill as I replace the u-joints and transfer case seals.

Sure wish I could find a manual (I have the '96 and '97 supplement service manuals which leave out a lot of useful details.) It took me 3 days to figure out how to set the clock in the radio!

 

[The Goat]

Depending on where you are, coastal and supertech both make a quality gl5 lube that is yellow metals safe.

While Im a proponent of synthetics, gear oil is one situation where, from a performance standpoint, there is no benefit for paying the extra coin.

Now oil, yeah...just because synthetic is cheaper per mile in the long run.

 

[Max]

Right or wrong, I take an opposite view of synthetics. I feel that engines benefit from frequent oil changes to remove the byproducts of combustion and the inherent moisture captured during normal driving episodes (particularly short distances).

Conversely, I feel that Syn's in gear boxes and diffs offer several benefits....they require changing much less frequently (cost spread over time), function well in a closed / clean environment and in the case of manual transmissions, provide for smoother shifting.

I'm a Redline fan for those reasons...
Red Line Synthetic Oil

FWIW, I could support Syn engine oil in very high performance engines or racing applications (where cost isn't an issue and frequent changes are employed) but for a daily driver? Naw.

 

[fordem]

While Im a proponent of synthetics, gear oil is one situation where, from a performance standpoint, there is no benefit for paying the extra coin.

Now oil, yeah...just because synthetic is cheaper per mile in the long run.

I'm sorry, but I have to disagree ...

First let me say that my opinion is formed after personal experimentation over a number of years and vehicles, this is no "regurgitation" of what I've read on the internet, or heard from a friend of a friend.

I run full synthetic lubricants in my transmission, transfer-case & differentials on every vehicle I own, and conventional motor oil in the engines.

I can feel the difference in the way the transmissions shift, I've seen the benefits of the full synthetic in that application - now - on an off road vehicle, it may not make that much of a difference that you're willing to pay the extra for the full synth, but on a sports car where a tenth of a second makes a difference, I can attest to the performance enhancements.

Additionally, as Max has pointed out, the drive-line lubricants are changed less frequently than engine lubricants allowing the cost to be spread over a longer period.

On the engine side - over time the oil becomes contaminated with combustion byproducts such as, soot (which is too fine to be removed by the filter), acid, moisture, fuel dilution - if the engine is operated long enough, the oil will become hot enough that some of the moisture will burn away, but the remaining contaminants are held in suspension until the oil is changed.

How long do you want to leave that toxic soup inside your engine, knowing that every day, the acids are eating away at your bearing surfaces?

Personally I'm changing it out, and I am not willing to pay the extra for the synthetics, and, please be reminded, this is after testing with full synthetics, and synthetic blends.

The last thing I want to leave with you - research the Castrol/Mobil One "law suit" - see where the Supreme Court allowed Castrol to redefine what a synthetic oil is, and then decide if you want to pay as much as you're paying for what is, in all probability, just a better refining job - are you actually using a synthetic oil or just a highly refined mineral oil?

 

[SuperMario93]

"Either an 80W90, a 75W85 or a 75W90 GL4 for the transmission & transfer case, depending on the climate; and a 90, 80W90 or 75W85 GL5 for the differentials.

I make one bad job and use 75W90 Mobil One full synthetic - it is a GL5, but it is safe for use in the transmission & transfer case."

if you have an AUTOMATIC transmission DONT USE GL4. in an automatic transmission you use Dextron 3 or Dextron 6. the rest is good though GL4 in the T case and GL5 in the diffs.