In my case, the gearbox is still on the car. So it's a case of accessing it from the underside of the car, removing the ruddy awkward filler plug with a shortened Allen key and using an electric pump to pump the old oil out. A job I relish - not!
The warmer the easier.
I use red line heavy shock proof ( red ) in the gear box and the de dion rear axle . Perfect for me in a 1989 Sprint Caterham .With other GL4 oil I tested some problems , with this one it is fine as the Original Ford Oil that is no longer available . The red line product is not corrosive withe bronze parts of the gear box .
It is possible with care to remove the top cover, however, you are working blind for some of the bolt removal / refitting. The important / difficult bit is relocating the selector plate in the slot in the lid.
Some people have also fitted a cap into the forward part of the lid to aid level checking, evacuation and filling. Mine has a welded on boss / VW sump plug others have used brass plumbing fittings.
It is possible with care to remove the top cover, however, you are working blind for some of the bolt removal / refitting. The important / difficult bit is relocating the selector plate in the slot in the lid
Just done this on another car, it's a bit of a pain, slow, but doable. My car has a drain and a top cover filler fitted with a cap / dipstick, fitted by BGH at a previous rebuild, and I can highly recommend both.
Where is the drain plug fitted? Is it tapped into the iron casting or one of the ally sandwich pieces?
The drain is in the aluminium sandwich plate, giving about a 90 - 95% oil drain.
If you have a top filler you can vacuum the oil out, talk about oil ATF is also fine and gives a better gear change from cold.
Thanks, Elie. Funnily enough, Opie Oils recommended ATF.
As it happens, I've only just got around to doing the oil change today. Using a 12v electric oil pump, I've pumped the old oil out, through the filler plug hole. About 1.3 litres came out. I'm about to refill it using Red Line MTL 75w80.
Never had a problem with Halfords 80w/90 GL4 mineral - Three Sevens two with Ford 5 speed & the latest with 6 speed.