<VV> Finding manual transmission oil locally?

[Joel McGregor]

I was catching up on emails and just had to say something.
This is a Corvair list and the OP was asking specifically about a Corvair "75w90 gl4 gear oil for my 65 4speed tranny".  All factory manual transmission Corvairs share oil with the differential so not saying differential specifically doesn't matter since you were answering a post about a Corvair transaxle.
In your reply you said " I would avoid these and use ATF or EP 90" and "Just steer clear of anything with 'hypoid' on the label." both of which would ruin his differential.
Frank is correct.
Flame away...
Joel McGregor

-----Original Message-----
From: VirtualVairs On Behalf Of Hugo Miller via VirtualVairs
Sent: Sunday, June 30, 2019 12:06 PM
To: virtualvairs at corvair.org
Subject: Re: <VV> Finding manual transmission oil locally?

Here is what I wrote - You will not find the word 'diff' or 'differential' anywhere in my post;

"As a general rule, synchromesh transmissions run best on ATF. What you want to avoid is hypoid oil, as this will allow the synchro cones to slip & slide without biting. I have known commercial ZF transmissions become almost underiveable when filled with hypoid oil.
The problem is that in the good old days, we had hypoid gear oils and we had EP (extreme pressure) gear oils. So you had EP 90, which was good for synchro transmissions, and Hypoid 90, which was not. The two were quite different.
But today, through the magic of modern chemistry, we see EP/hypoid oils, which serve both functions. I would avoid these and use ATF or EP
90 if you can find it.
I'm not up to speed with the GL numbers - Google will tell you more than I can. Just steer clear of anything with 'hypoid' on the label."

  The reason I omitted to mention differentials was that we were talking about synchromesh gearboxes. I was trying to explain in general terms why hypoid oils, and that includes modern EP/Hypoid oils, are unsuitable for synchromesh gearboxes. This is not 'bad advice' as you claim - it is perfectly sound, and the effects of diregarding it can be quite surprising.
  One would hope that the original poster is aware that his car shares the oil between gearbox and axle, so would treat my advice about gearbox oils accordingly, although it does pose something of a conundrum. On balance, I would be more inclined to put EP oil in a differential than to put Hypoid oil in a synchro box, but neither is ideal.


On 2019-06-30 17:48, FrankDuVal via VirtualVairs wrote:
> Hugo, you say "but I wasn't actually suggesting putting ATF in a 
> diff."  But you did!
>
> By not knowing the transmission and differential on manual 
> transmission Corvairs share fluid.
>
> Since PG Corvairs have separate fluid, you can run GL5 in their 
> differentials with no problem.
>
> Just adding this email in for the archives to make sure no one follows 
> the bad advice in the future.
>
> I've shared bad information in the past also.... You have now joined 
> the club. ggg
>
> Frank DuVal
>
>
> On 6/30/2019 10:36 AM, Hugo Miller via VirtualVairs wrote:
>> Thank you, but I wasn't actually suggesting putting ATF in a diff. I 
>> went to some lengths to explain that (hypoid) crown wheel & pinion 
>> gears (ring & pinion if you prefer) require a different oil from the 
>> standard Extreme Pressure stuff, and I explained why hypoid oil was 
>> unsuitable for synchro cones. It has less to do with the oil 
>> attacking the soft metals (in fact I've never seen a sybchro cone 
>> corroded in this fashion) and everything to do with making the cones 
>> slide over one another instead of biting, which can literally make a 
>> vehicle un-driveable, on commercial gearboxes anyway.
>> But I've already said all that - the confusion arose because my car 
>> has separate oil for gearbox and transmission and I didn't realise 
>> that a 4 speed shared trans oil while a PG didn't. Not that this 
>> affects the validity of my arguments of course.
> _______________________________________________
> This message was sent by the VirtualVairs mailing list, all copyrights 
> are the property of the writer, please attribute properly. For help, 
> mailto:vv-help at corvair.org This list sponsored by the Corvair Society 
> of America, http://www.corvair.org/ Post messages to: 
> VirtualVairs at corvair.org Change your options:
> http://www.vv.corvair.org/mailman/options/virtualvairs
> Archives: http://www.vv.corvair.org/archive.htm
> _______________________________________________

 _______________________________________________
This message was sent by the VirtualVairs mailing list, all copyrights are the property of the writer, please attribute properly. For help, mailto:vv-help at corvair.org This list sponsored by the Corvair Society of America, http://www.corvair.org/ Post messages to: VirtualVairs at corvair.org Change your options: http://www.vv.corvair.org/mailman/options/virtualvairs
Archives: http://www.vv.corvair.org/archive.htm
 _______________________________________________