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Semi-synthetic gearbox oil


Pathlander
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I tried searching and haven't found much on the subject. With gl-4 being harder to find (especially at a reasonable price), I found some semi synthetic Ravenol for a decent price. I hear synthetic shrinks seals, causing leaks, and I also hear that is a myth. I plan to use the same lubricant in my transfer case, so the price is definitely a factor. Should I give it a shot? Or just bite the bullet and buy MT-85/90? Any advice is much appreciated.

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In My experience on my 95 D21, I never had an issue running full synthetic aside from the price. From my previous readings on the topic, I understand that it's the sulfur in the GL5 oil that causes the excess wear on the synchronizers. Full Synthetics usually don't have the sulfur. I Haven't done that kind of fluid change for my WD21, but I'll probably go that route if I keep the animal that long ;) Somewhere along the road, I'm going to have the transmission out and put new seals into it then and fresh fluid to boot... Till then.... Fun fun fun...



You should check the service manual for the transfer case. I believe it takes Dextron II ATF.



As far as causing excessive leakage because the seals shrink, No. The Seals were probably already worn and Synthetic oils are slipperier and tend to leak more. If you're only leaking a little in the first place, it's not going to be a noticeable difference. You'll have to continue to keep an eye on it, like you normally would if you know you have a leak.


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Synthetic oils don't shrink seals like a lot of people believe, they have a high detergent package and causes all the old crud that's sealing a worn seal to be removed and thus letting the oil leak out.

 

I personally use penzoil snyncromesh in my transmission. It's cheaper than GL-4 oils in my area. It's in a yellow bottle and I really like it, smooth as butter. I've never used it in a transfer case but I don't see anything saying I can't. I mean you can use atf in there if you really want (factory filled on auto equipped models)

 

Sent from inside my potato

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It is usually a good idea to run the same fluid in the transmission and tcase. That way, if the seal fails there is no mixing of different lubricants. So ATF if you have an auto, and gear lube if a manual.

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Damn, I ended up ordering the mt90 a few days ago. I wanted to use synchromesh, but read mixed reviews on here and it didn't say Nissan on the bottle. Oh well, at least I know the redline will work fine. Bought a couple quarts of Lucas stabilizer too. Should I bother adding any of that to my transfer case? Also, is there more than one model of manual transmission in the states? I guess what I'm trying to ask is if I will definitely need to overfill it.

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They moved the fill hole up a little in '96 from what I've read, so if the rig is later than that or has already burned up a trans and had a later one swapped in, no overfill is necessary. Otherwise, plan on overfilling it.

 

I haven't heard of stabilizers being used or needed in manual transmissions, and without knowing what's in it, I'd have reservations about mixing it into new oil.

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