<VV> Finding manual transmission oil locally?

Hugo Miller hugo at aruncoaches.co.uk
Wed Jul 10 03:13:45 EDT 2019


"Catching up" being the operatve phrase! You are of course correct, but 
we've been over this. What threw me was that my Corvairs do NOT have 
integrated gearbox and axle oil. I simply had no idea that the manual 
design would be so different from the automatic.
In my defence, this is what I said when somebody alerted me to this a 
while back;  "Here is what I wrote - You will not find the word 'diff' 
or 'differential' anywhere in my post ..."


On 2019-07-10 01:12, Joel McGregor via VirtualVairs wrote:
> 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.
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