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75w90 vs 75w90NS

Discussion in '308/328' started by rjd2, May 21, 2023.

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  1. rjd2

    rjd2 Karting

    Jul 28, 2016
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    #1 rjd2, May 21, 2023
    Hey folks, I have hammered the search function on the ideal transaxle fluid that is best for the synchros (1978 US spec 308 GTS, fresh motor and trans rebuild), and am feeling a bit spun out with too much info. It seems that the consensus is that 4 quarts of 75w90NS and ~1 quart(I am aware that ~4.5 quarts is an average volume) of of regular 75w90 is the way to go? I recall the shop saying that there was an "additive in redline now, and we don't use it anymore". I mistakenly pulled the gear oil plug when doing an oil change, and replaced it with the standard Redline 75w90. I want to put the proper oil in that will maintain the life of the freshly built transaxle. Is there possibly an alternative product that is "definitively appropriate" in the gearbox? Thanks for the help.
     
  2. waymar

    waymar Formula 3

    Sep 2, 2008
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    Wayne Martin
    #2 waymar, May 21, 2023
    Redline MT90 or MTL is the options I’ve used with great results….. many others will chime in as there are many detailed threads on this topic.
     
  3. mike996

    mike996 F1 Veteran

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    #3 mike996, May 21, 2023
    MTL!
     
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  4. classicalfas

    classicalfas Formula Junior
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    #4 classicalfas, May 21, 2023
  5. GordonC

    GordonC F1 Rookie
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    #5 GordonC, May 21, 2023
    That WAS the consensus, the Redline GL5 cocktail mix... 10 YEARS AGO! Since then, Ferrari mechanic Brian Crall (who posts here as 'Rifledriver' has posted that he used regular Redline MTL in the transmission of his own and his customers' 308/328 cars. One big factor - Redline 75W90 and 75W90NS are GL5 gear oils designed for extreme pressure requirements in hypoid gears, such as in traditional differentials. There are no hypoid gears or extreme pressure requirements in the 308/328 transaxle. Good shifting characteristics seem to be optimized by use of MTL.

    When I bought my 308 in 2013, I tried the Redline 3:1 cocktail mix. A few years later, I switched over to Redline MTL, and shifting ease, precision, speed improved - and cold 1-2 shifts were noticeably improved. If you search this section for 'Redline MTL', you'll find a lot more threads supporting that for use in your transaxle than the now-obsolete Redline 75W90/NS mix.

    Gordon
     
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  6. ginoBBi512

    ginoBBi512 F1 Rookie
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    #6 ginoBBi512, May 21, 2023
    I have used Shell full syn for my 89s gearbox for many years. I now have the Redline full syn gearbox oil and it works just as good , if not better.

    Big G
     
  7. Edward 96GTS

    Edward 96GTS F1 World Champ
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    #7 Edward 96GTS, May 21, 2023
    mobile 1
     
  8. mike996

    mike996 F1 Veteran

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    #8 mike996, May 22, 2023
    I have no idea if the transmissions of the 308/328 are identical and I realize it's only one car and therefore not at all scientific but I have used five different well-known gear oils in my '89 328. MTL worked far better than the other four. It shifts much more smoothly and has virtually no cold second gear reluctance. Additionally, with the other gear oils the transmission would "scrounch" sometimes when rapidly shifting at 7000+ RPM at WOT; the MTL never does.
     
  9. miketuason

    miketuason F1 World Champ
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    #9 miketuason, May 22, 2023
    I went from Redline 75w/90 NS to MTL and never looked back.
     

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