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Re: Changing oil (gearbox?)

Subject: Re: Changing oil (gearbox?)
From: (Graham McCann)
Date: Mon, 8 Jan 1996 09:40:31 +1100
>  Okay, here's a real newbie question.  With the Kansas City temps down
>below 10 degrees this weekend, I'm wondering why the DPO for my '78 MGB had
>20W50 oil in the crankcase.  Having never encountered anything but 10W40 in
>my previous life, I just figured that 20W50 was what I was suppose to use.  

On a 1978 MGB the oil filler hole is on the side of the gearbox, not on top
as in chrome bumper models.  It is difficult to refill it without some sort
of pump, especially if it is cold as the oil will not flow easily.  Engine
oil is the recommended lubricant.  There is an argument for using 80W/90
gear oil in the gearbox (as was the factory recommendation for the V8
model).  Despite popular opinion, gear oils use a different viscosity index
to engine oils and it is in fact slightly less viscous than 20W/50.

Both the drain and filler plugs on a rubber bumper MGB are gas plugs ie,
they are tapered in the threads so have no gaskets, but may also be a bit
hard to loosen, especially when you are upside down under the car.  Because
the gearbox is relatively long and thin having the car on any sort of slope
(on ramps) can give you an incorrect quantity when filling it.  You fill it
until the oil just starts to run out the filler hole so you can see the trap
of a car on a slope.  Try to find a downhill driveway to use the ramps so
that the car finishes up level and you can still get under it.  If this is
not possible I suggest you get it done on a service station hoist.
Graham McCann  Rivett, ACT. Australia
06 2889055

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