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348 Gear Oil experiment

Discussion in 'Technical Q&A' started by Bmyth-FDC, Dec 2, 2003.

  1. Bmyth-FDC

    Bmyth-FDC F1 Rookie

    Oct 4, 2002
    2,742
    Southern California
    Full Name:
    Byron
    Hey guys...
    I know there are tons of discussion threads about gear oil... mobil 1 v. agip v. redline v. just about anything...

    After using Mobil 1 and Valvoline brands of gear oil, I was still experiencing very notchy shifting while my oil temps were cold. Very difficult to engage 1st. I think the real problem is in my synchronizers, but before I went and switched those out, I thought I would give another oil a chance...

    Redline Synthetic 75W90NS - "NS" for non-slip. (no friction modifier additives in this oil, similar to Agip non-slip formula)

    I'm not going to swear by this for every car's application, but after I replaced my mobil 1 gear oil for this oil, it seems to perform better at cold temps for me. I used 4 quarts of 75W90NS and topped off with 1/2 quart of regular Redline 75W90.

    Anyways, just thought I would pass along this info. I'll keep everyone posted on the long term durability and my satisfaction with this oil - good or bad... I'll let you know.

    -Byron
     
  2. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,633
    USA
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    Hugh G. Rection
    Byron,
    Since the regular Redline has 4% friction modifier, what is the percentage you end up with? I know Dave at Redline, says that you want around .5 to 1% in a Ferrari transaxle....

    I am using the Redline 75w-90 NS with .5% slip additive, but am still getting a little bit of noise/chatter from the limited slip on a sharp 90 degree turn when starting out from a stop.

    I've chosen to "live with it" rather than add any more additive at this time.

    Shifting is very good, with no crunching of the synchros, that I was getting from the Mobil 1 after several months (and thousands of miles) use.
     
  3. Bmyth-FDC

    Bmyth-FDC F1 Rookie

    Oct 4, 2002
    2,742
    Southern California
    Full Name:
    Byron
    Dave,
    That's a good question. Well, given that I am using 1/2 quart to dilute with 4 other quarts with no slip additive. Unless I'm doing my math incorrectly, it's probably near the range of < 0.5% slip total, probably at or near 0.25% b/c of residual oil that was in the transaxle. I haven't heard the chatter on mine yet, but since I just added it on saturday, I'm sure it's b/c I just haven't spent enough time in the car. I will check again this weekend and let you know. I'll do the sharp 90 degree turn from full stop and see. The Mobil 1 worked well before my gearbox rebuild, but since then, it seemed to "crunch" my synchros - that's why I'm experimenting with the redline.

    -B.
     
  4. 4re gt4

    4re gt4 Formula 3

    Apr 23, 2002
    2,279
    Roseburg, OR
    Full Name:
    Hans E. Hansen
    Dave: Are you sure your getting diff chatter? My car will 'slide' a tire on sharp corners under acceration. It slips, grabs, slips. But it's definitely the tire, not the diff. In my old Corvette days, you noticed posi chatter on tight corners *at low power*. It would crunch and kind of jerk the car around. Under significant power, a tire would simply slip. GM Limited Slip Additive was the standard answer to American muscle car diff problems.

    I just changed gear fluid. I had 1 qt 75W90 (regular) with roughly 3 quarts 75W90NS. It gave me a 4th gear 'crunch' at real high rpm that I didn't have before. This time I used straight "NS" and got rid of the 'crunch'.
     
  5. hanknum

    hanknum Formula 3

    Nov 1, 2003
    2,040
    Santa Barbara
    Full Name:
    Henry
    Byron,

    I did the exact same thing you did about 2 months ago. I previously had Agip in mine w/o too much problem, but after the umpteen gear oil threads we've had decided to try Redline (it needed changing anyway). I used the 4 quarts of NS and topped off with the other. Like I said I didn't have much crunching before and I don't now. Second gear when cold seems a tad bit better though.

    Henry
     
  6. matteo

    matteo F1 World Champ

    Aug 1, 2002
    13,748
    On a plane somewhere
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    Heir Butt

    Changing your syncro's seems a bit over the top, at least at this point.

    GM makes a limited slip diff additive in a sm 7oz bottle. I had the same problem as you for awhile. I added 14 oz to the transmission and after 50 miles, the diff chattering and the cold shifting issues went away.

    Redline would make a plus too.
     
  7. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    16,633
    USA
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    Hugh G. Rection
    Hans,
    You may be on to something there...that is, I may be diagnosing the noise incorrectly, and my limited slip diff is working as it should.

    In any event guys, careful with the slip additive, as it works AGAINST the synchros, so don't add it, unless needed, and too much will cause the synchros to "crunch".
     
  8. Bmyth-FDC

    Bmyth-FDC F1 Rookie

    Oct 4, 2002
    2,742
    Southern California
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    Byron
    Good point... I had considered adding the GM additive, as well as the Redline. However, at this point, I think by mixing with regular 75W90, I am getting marginal additives (< .5%). That may just be enough, while NOT inducing chattering and crunch.

    Changing out my synchros is not an alternative I would like to and want to entertain at this point.

    Maybe the long term solution is just shift 1 to 3 while cold! :) LOL.
     

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