[FC] <VV> Drain plug installation--64 FC manual transaxle

[Rad Davis]

Ken already covered this, but I'll reinforce it here - lubricant 
technology, like paint and coating technology, is completely different 
than it was in 1961.

Just as the stock paint job on a '61 Corvair could be expected to look 
good for two years and protect the car for perhaps five, whereas a 
current technology paint job will last the life of the car, which , 
incidentally, is a lot longer than the 70,000 - 120,000 miles the 
Corvair was designed to last.

We still have to change engine oil because our (gasoline) engines use up 
oil additives in their normal operation.  The only reason to change 
trans/diff lubricants is because they pick up debris from the operation 
of the gears that must be removed periodically.  'Lifetime' (200,000 
mile) lubrication is quite possible if the surface finishes on the parts 
are sufficiently fine and the chemistry of the materials sufficiently 
passive at initial assembly.  Neither was the case in 1961.

As with most other mechanical things, gear trains seem to require 
regular oil management during break in.  After they're done making swarf 
during break in, you're essentially done with reasons to change the 
fluid at a short interval.  Debris is still created by synchronizer 
clutches in a manual gearbox, so they need a fluid change every 60,000 
miles or so.  All of the data I can find for synthetic gear lubes 
suggests that hypoid final drives should be OK for 100,000 - 500,000 
miles after break-in is complete.  So if you run the cheap stuff, change 
it every 50 K or so in both units and be happy.

If you're shearing gear oil down in this decade, it's because you are 
using the wrong lubricant, particularly on something as gently loaded as 
a Corvair transaxle attatched to a (non-turbo) Corvair engine.

- Rad Davis


James Davis wrote:
> 1961 Shop Manual states drain and refill the transaxle every 10,000 
> miles.  The EP additive in GL-4/5 is consumable (it looses it 
> effectiveness) and should be replaced at the specified interval.
> Jim Davis
>
> n2vzd at aol.com wrote:
>   
>> i have not seen the need to change the fluid in the  STD transmission  , or 
>> the differential unless other damage has occurred , in which case it would  
>> be all apart in my parts washer getting cleaned properly , and bearings  
>> carefully checked , along with ALL new seals etc. then i put a strong magnet  
>> inside to hold any damaging filings that might happen., oh i put STP or such 
>> in  with the grease so lube does not drain off when setting.
>> regards, tim colson
>>   
>>     
>
>
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