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Favorite/Recommended Gear Oil for 4-Speed Tranny


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This may have been covered before and I just missed it, so if I did someone please just point me in the right direction... but I have been searching the forms for the past two hours and have come up with not a lot.

 

So anyways, I was wondering what everyones favorite gear oils/lubes are for the EA81 4 speed trannys. So far it looks like Amsoil is a good choice from what I have read. I was hoping to be able to find something a little cheaper that I can get off the shelf that would work nearly as well. I know JesZek loves Motul 80W-90, but from what I have found online that stuff is insanely expensive for my thin wallet. Although Im sure it works like wonders.

 

Has anyone tried Royal Purpel's 75W-90 synchromax? I know its just about as spendy as Amsoil, but I am curious if anyone has any experience with it so we can compare. Right now I am running the walmart supertech 75W-90 and i want to get something a little higher quality in there so I can make this little tranny last.. and shift easier in the winter months

 

5-speeders are more than welcome to give their experience as well! As so far it looks like they take the same oil/lube as the 4spds... 

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I use royal purple in my lsd rear diff because of the friction modifier which worked noticeably better than some other brands i've used. I've been using carquests gear oil by the gallon without any problems in 4 and 5 speeds which was fairly cheap. Never have had a problem with super tech, castrol, valvoline, or napa brand either they all work the same. During the winter you should go with a lighter oil to see if that helps.

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I use Amsoil.  It made a huge difference in my 76 & 78 4 speeds in winter.  With regular gear lube, it would barely shift from 1st to 2nd the first few time on cold mornings.  With the Amsoil, it shifted the same as summer even in winter.

Yes, it is spendy, but you can run it for 100K miles.

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... I know JesZek loves Motul 80W-90, but from what I have found online that stuff is insanely expensive for my thin wallet. Although Im sure it works like wonders. ...

 

I did not know that Motul oils are that expensive in the USA, here in Honduras, Motul is being sold at competitive prices, only a little higher than the regular oils; I believe it is because the commercial agreement with Europe = Lower tax rates; also we have similar agreements with USA, Mexico and Canada. Sorry for the off topic info.

 

I have no personal experience with Royal Purple, but I have readed wonders regarding its friction modifiers, so Also I can suggest you to use that oil; however, you must consider that almost any Gear oil, classified as GL-5 and having the proper SAE grade, will suffice for the application, if you change it on a Regular Basis.

 

Kind Regards.

Edited by Loyale 2.7 Turbo
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Despite its Higher price, Motul with MoS2 (Molybdenum Disulphide) has paid for itself, because I change it after longer periods of time, and it saved my 5 speed Manual transmission / differential on my "BumbleBeast" after the horrid Sabotage it suffered, some time ago. The MoS2 managed to leave a film that protected the moving parts from shearing, despite the added liter of water.
 

GearBoxOil.jpg

 
And also, it solved the Hard shifting to first gear, on a Ford Ranger; and other similar issues like noises, etc... on the cars on which I've used Motul, elongating the Transmissions and differentials Lifespan; but it has to be the 
Motul with MoS2, not the regular one.
 
Kind Regards.

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I've always used ATF.

 

I've read about using ATF on Manual Transmissions, but I bet that such custom could shorten their lifespans due to the increased shearing; unless ATF is indicated as the proper Oil for a Manual Transmission, like certain Mitsubishi Eclipses, on which I've worked.

 

Kind Regards.

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I use Redline MT90 in my Brat. It is a GL4 which is recommended in the owners manual. Pricey and not usually on shelves. It has helped my nearly 240k transmission out. Though I used it first many years ago. My Brat would occasionally want to scratch gears shifting, rarely ever does it now. Yes, the clutch cable is properly adjusted in case any one wonders.

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I use Redline in my '85 Brat (5 speed), and '84 wagon. Any top shelf gear oil will be an improvement, and I've found that there's only a couple of bucks difference between brands. Either way the shits not cheap, but once you get it in you will forget about the cost. I went with Redline 'cause you can find it pretty much everywhere.

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