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Yet another gear oil question

2716 Views 21 Replies 7 Participants Last post by  toobroke
Has anybody actually tried the Valvoline Synchromesh oil? I'm reviving a 2009 451 that was towed behind an RV in gear, fubaring the engine, clutch and transmission. I got the car for for free and have rounded up the parts to make it work. Once it runs, it will be used at low speed for non-essential but fun short trips, like tens to hundreds of miles a year. I'd like to find a gearbox oil good enough for that and readily available at local suppliers. I'm very skeptical that use of anything other than BOT 328 will actually cause mass death and destruction, but I'm curious whether any members have tried the easy cheap locally available options. My local NAPA evidently stocks the Synchromesh at a low cost. Does anybody know of any reason I shouldn't try it?
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Do a search, volumes have been written on here. It needs to be a GL4 lubricant. DO NOT use GL5. GL5 will eat the brass synchros in the transmission.
I personally used Redline MT90 in mine. Now has over 219K Miles on it and running fine!

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I have read tons of threads here, but didn't find an answer to this question. Lots of "this stuff is expensive but awesome" or " BOT328 or death" kind of answers, but nothing about "good enough to get by". I'm just looking for something locally available and low-cost for a Smart that will get extremely limited use.
On the Valvoline website the "PI Sheet" says GL-4....

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Thanks! Should at least do no harm.
Looks a little thin to me.

cSt is 49.9 at 40º C, and 8.8 at 100º C

Compared to 132 and 17.5 for Mobil 1 Delvac 50,
82 and 15.5 for Red Line,
and 102.4 and 15.9 for AMSOil Severe Gear...
Thanks. I was wondering about viscosity. I'll look at other options.
I'm installing the replacement trans today and plan to have it driveable for the weekend, so I will go with something I can pick up locally. It will mostly be used as a mobility scooter/UTV for my wife to get around a few acres, so it doesn't need to be high-performance in any sense.

Thanks for all the suggestions.
Because GL5 oils state they cover GL4 as well.
Some of us may interpet that as sufficient.
GL5 definitely doesn't automatically cover GL4. GL5 isn't an improved spec over GL4, it is a different spec entirely. A major difference is compatibility with "yellow metals" (brass, bronze and copper) as used in synchronizer rings. Some GL5 products claim to cover both specs. It may be possible, but I haven't seen definitive objective proof.

Hopefully a tribologist will come along and clear this up for all of us. In the meantime, I've filled my 451 trans with leftover cheap 85w90 GL4. It may not shift optimally, but at least I don't think it will eat the synchro rings.
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