M5 Fluid Change
Just changed the lubricant in my '84 5 speed tranny. After draining the old oil, I noticed another larger drain plug further forward on the transmission. This one is on a flat cast aluminum bottom plate with 10mm bolts around the perimeter. So I drained this section too. Both drain plugs have magnets. There are also two fill plugs. Can anyone explain these two reservoirs which seem to be connected?
The Haynes Manual says to use SAE 80. I used Castrol 80W90 'Hypoy C'. Will this be ok? Seems pretty thick, esp. for the cold winters. The old oil was quite heavy too, with that gear oil odour.