Use Castrol Mercon V (ATF) in a 5 speed MT?

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6
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NM
My first post and my mechanic of 25 years recommends it. Well that's what I'm about to do 'cause my '01 Frontier 6cyl 4x4 is real notchy. So I plan on draining the trans and transfer case and replacing both with Castrol Mercon V Thought I'd post for feedback
 
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7,430
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beaver land EH?
Betta stick with the type of MT gear oil that your car manufacturer recommends and don't play scientist. Afterall: A/T fluid is never known to contain AW/EP additives and anti-foaming additives that M/T gearbox requires (esp. those helical cut gears) Q.
 

LeMarque

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6
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NM
Just to say, my 'new' '01 5sp feels like an old Ford tractor. Per the manual API GL-4*1 Viscosity SAE 75W-90 only 80W-90 for the differential and 75W-90 for the transfer case are preferable for ambient temperatures below 104°F (40°C).
 
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LeMarque

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6
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NM
err ... it unfolded like this. I actually thought I read somewhere that ATF was used (on rare occasions) and while discussing this with my mechanic, I brought it up and we got into a long discussion. So after digesting all the feedback here and on the Nissan forum, I'm having second thoughts. There's no Amsoil dealer here so I'll try something like Mobil1 and leave the ATF as a misunderstanding on my part. Sorry for the aberration
 
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5,949
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Texas Hill Country
Check out the amsoil site for what that trans spec's and make sure you meet the spec. I put Mobil1 MerconV fluid into a saturn ion MT last year. It says on the bottle meets the DextronIII spec. Many of the newer manual transmissions take automatic trans fluid, not gear oil.
 
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7,430
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beaver land EH?
To original poster: if your transmission calls for MT gear oil then MT gear oil it is. Instead of risking unncessary wear and tear on our gearbox by putting in ATF(if it calls for GL4/GL5 75W90), which would accelerate the wear on the helical cut gear contact surfaces as well as bearings and foaming issues, instead why don't you give different brands of GL5 oil a try? (Amsoil, Pennzoil, Castrol syntec, etc.) (these 2 fuilds are not interchangeable due to fundamental differences in gearbox design/operation/requirements) So, if your MT box calls for GL4/GL5 spec'ed gear oil, then go for it. Lastly: (to JustinH): even seen a peterbuilt's MT gear box running on AT fluid, hauling 40tons worth of stuff down the freeway? Also: do you have UOA on our ATF loaded MT gearbox to show us your wear reading? Q.
 
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beaver land EH?
My Honda fit uses their own blend of MTF and despite of many board posters recommending using 10W30+otc additives to replace it, instead I opt for Idemitsu MTF-II which is semi-syn and totally complies with Honda's spec. (in Japan, they already have full-syn MTF-III available from official Honda dealerships now, and yet in N.A., they are still selling the old, MTF (non-II) oil that is blended by some domestic supplier and the shift sensation as well as longevity is poor). Q.
 
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19,479
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Chicago Area
ATF is thin and will be useful in very cold weather, but it is not made for manual transmissions or synchro shifting ability. It is OK, but certainly not the best option.
 
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7,430
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beaver land EH?
To OP and many others: It's your call if you want to deviate from what the original designs call for. If there's any damages done to it, it's gonna be yours (and not us). Afterall: it's your vehicle and it's your money. Q.
 
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8,756
Location
RI
Anything other then gear oil will add wear to your transmission. Nissan has an excellent 75w85 GL4 that can be used. It is a cure for your shifting blues. Amsoil MTG, Idemitsu MTF, or Redline MT90 are some other options. Stalube, Pennzoil,... also have GL4 90wt gear oils but are more difficult to find. Motul Gear 300, Synlube MT, Eneos, RoyalPurple Maxgear, and Torco RTF are some GL5 90wt options. I would not use an ATF. NM isn't a cool enough climate to go thinner.
 
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9,679
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Central Coast, Calif.
I also agree with using an MT specific lubricant, they are different than common gear oil. How come the sets of gears in an AT don't wear excessively with only ATF lubricating them? I understand there are no syncros but there are still planetaries and other types depending on design.
 

LeMarque

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6
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NM
[quote=mechtech2 It is OK, but certainly not the best option. [/quote] Gotta ask, what's the best option?
 
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8,756
Location
RI
Manual transmissions are splash lubrication. Automatics tend to have pressure and flow that manuals dream off. Planetary loads are different then gear:gear loads. The list goes on and on. If you require gear oil, use it.
 
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57
Location
Georgia
Use Redline MTL (Manual Transmission Lubricant) Your lube related shifting problems will be over. Consider that the problem might be the shifter seat bushing(s).
 

LeMarque

Thread starter
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6
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NM
Oh well I just picked up Mobil1 75-90 Synth. Maybe next time. Thanks for all the replies and I'll post back the results.
 
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475
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snow and sun
I drained the "life-time" BMW E36, 1998 M3, 5-speed fluid, with 85k on it and it looked like dark green ATF. Ran Red Line MTL with very good results. Then did my normal order with Bavarian Autosport and they sent me Redline D4 (or is it D5?)Automatic trans fluid. And the shifting cold and warm is fantastic! Others use this fluid too. This is also recommended by other BMW E36 owners.
 
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