75W-85 vs 75W-90 for MTF?

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Jan 27, 2005
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My owner's manual calls for 75W-85 (API GL-4) MTF but I just flushed that and put Shell Spirax S 75W-90 (API GL-5, MT-1, pour point -45C) synthetic I got from my brother's supply. The transmission was very stiff (until warmed up) on cold winter days with the OEM stuff. Could it have been dino oil? Is 75W-85 readily available in stores? The Spirax did great when I put it in my former '05 Corolla. Shifting when cold in the winter was just like in the summer and fast idle speed almost gained 200 RPM. I hope to improve the cold shifting of my Sonata the same. So far in summer temps, the change is almost unnoticeable.
 
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redline and amsoil make excellent mtf lite. in my own tranny, i just mix 50:50 PZ synchromesh with Mobile 1 5w30 EP - both cold weather and hot weather shifting is excellent, 1995 Mitsubishi 5 speed. manual calls for 75w85 gl3.
 
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75w85 is not readily available in stores. But, any automaker that has a vehicle taking 75w85 will have their version available at the dealers parts department. I've seen 75w90's that were blends. So, 75w85 should be easy enough to blend without too much 'synth'. Unless it is labelled full synth, it isn't! Redline MT90 can be thinned with 25%-50% MTL to make your 75w85. I would guess that Amsoil MTG/MTF can be blended the same way. Hyundai/Kia...just recently stepped down from 90wt to 85wt to improve performance. On cold days, just about any transmission is a little stiff. Both fluids being a 75w, I would not expect a 90wt to shift any better when cold. Manual transmissions are such a small percentage of the US market, and usually lifetime fill(read your maintenance manual for intervals), that I truly don't expect wallyworld or even the local autoparts stores to stock any, any time soon. Pretty popular weight overseas.
 
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Maybe after a million miles of usage, run underfilled and seriously overheated for an extended time, and after being soaked with water after taking the car submarining.....or combination of the above.... I haven't found a GL5 that WASN'T yellow metal friendly with regular 30k intervals in a normal environment. If there is no maintenance, you overheat the fluid, and at some point it takes in any water, any fluid can be unfriendly.
 
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Yeah... GL5s are buffered for the last two decades or so. Since the car in question is in Canada with cool winters, the lighter gear oil would be wise. But normally, it would not make much difference between the two grades mentioned.
 
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 Originally Posted By: unDummy
I haven't found a GL5 that WASN'T yellow metal friendly with regular 30k intervals in a normal environment.
That attribute of GL5 is real and can destroy transmissions even in short period of time. Different transmissions have varying amount of those metals, but the use of GL-5 will cause wear regardless. There is a reason the vehicle manufacturer recommend GL-4 for manual transmissions, which most do. If you want your vehicle to last 200k, put the right fluid in. You're playing the lottery when you use GL-5; Odds are against you that the GL-5 will cause premature failure-- Often much sooner than you'd think.
 
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Our Toyota Yaris specs either a GL-4 or GL-5 75W-90 lubricant and at first fluid change I put in Chrysler's bottling (#4874459) of Castrol's Syntorq LT, which is a 75W-85/GL-4. I wasn't pleased with it and had some gear clash in all temps, although stiff winter shifting was not a problem. Have since switched to Amsoil MTG and will be using it from now on.
 
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Consider RL MTL (GL-4). 2007 Sonata manual, 13K with this product and good results. Local Hyundai Dealer has 75W-85 synthetic.
 
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My Unimog calls for 75W-85W of a particular specification, Castrol Syntrans or one of 3 others, none of which are obtainable in the US. I'm thinking about a 50-50 mix of Mobil Synthetic Trans Fluid 50 and MSTF Arctic. Definitely needs a GL4 synthetic, NOT a GL5 since it has synchros. I have 2 gallons of RL MTL for top-off in case I get a leak (it takes 14L). Maybe MTL for complete fluid change? The owner's manual for North America calls for MSTF 50 but the worldwide Daimler database calls for 75W-85W, so I think 50, even synthetic, is only suitable for warm/hot climates. Charlie unimog U500/Unicat camper
 
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Nissan, Kia, GM, Dodge, Hyundai, Mitsubishi.....all have 75w85 GL4 fluids available. You can make your own my mixing 25% Redline MTL with 75% Redline MT90 or do the same with Amsoil's MTF/MTG..... Until someone can show me a GL5 related yellow metal failure not caused by neglect or abuse, it has NEVER happened. BTW, in the hundreds of manuals that I've seen apart, the so-called yellow metal damage wasn't there and many had GL5 gear oil(typical dealer or quicklube bulk oil). This was before the pro-GL4 onslaught and the crybabies who don't know how to shift a manual. We used good ol' incompatible toxic to the manual transmission bulk oil for indefinitely. And, then a couple years ago, the internet created the yellow metal scare. #*^&% the hearsay! With 300k miles on one of my 1983 synchronized transmission, it shifted its entire life on Mobil1 GL5 75w90 gear oil with a change out during every 50k clutch job. My only manual transmission failure was caused by 'water' and wasn't saved by the GL4 that I kept it filled with, and the synchros were toast as was the fluid, bearings, bushings, gears and just about anything in contact with the water/oil/rust blob of goop lubricant.
 
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 Originally Posted By: unDummy
during every 50k clutch job.
You needed to change your clutch every 50K miles? In 5-600K miles of manual trans driving, I've never had a clutch wear out. Charlie
 
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Since GL4 has approx. 1/2 the sulfur corrosion causing stuff as GL5, why is that not considered a problem? It is buffered chemically to not be a problem, that's why. And you need heat and moisture, anyway. Most GL5s are for hypoid gear protection and they are not good with synchros. That is the real problem.
 
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Nope, it was a trait of the car. The clutch would blow at will and by 50k, was slipping. They would actually disintegrate at a stop sign or redlight while sitting in neutral. Engineering defect! My Mazda on the other has 18 years old and on the original clutch. Why means nothing. Proof does.
 
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Hello guys, I am actually having a similar problem with the choice for MTF for my all wheel drive Nissan Qashqai. It seems like Nissan recommends API GL4 75W-85 for all wheel drive and API GL4 75W-80 for front wheel drive vehicles. I have no problem finding GL4 75W-80 or GL4 75W-90, however 75W-85 seems to be problematic (well, I guess, I can get it from dealer if I go there in person). Is there any issue I may have if I use GL4 75W-80 or GL4 75W-90 ? If I check Castrol web-site and use "castrol finder" I can see that it recommends SYNTRANS MULTIVEHICLE 75W-90 API GL4 for my car. The same story with differential and transfer case: Nissan recomends API GL5 80W-90 and Castrol recommends SYNTRAX LONG LIFE 75W-90 API GL5. Should I trust Nissan in terms of viscosity or Castrol? smile
 
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Redline MT-85 should also suit your application well and is easily available online with free shipping.
 
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badtlc, I guess what you are saying is that I should stick with Nissan's recommendations, correct? smile I doubt I will be able to buy Redline in Switzerland. My choices here are mostly European made oils.
 
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Originally Posted By: volodymyr
badtlc, I guess what you are saying is that I should stick with Nissan's recommendations, correct? smile I doubt I will be able to buy Redline in Switzerland. My choices here are mostly European made oils.
I know redline is available in Europe but I have no clue how much of it or if its near you. Fuchs makes a 75W-85. Can you get that? Castrol, Valvoline, Gulf, etc. all make it too. I am finding lots stuff from online European stores that should meet your owners manual specification.
 
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