the modern multigrade gear oils are quite thin so shouldnt bugger oil pump ,its baulk rings that could suffer,but yours are worn anyhow
id never normally put an ep oil in a gear box not designed to use it, baulk rings are easily damaged as they are designed to move just enough oil from gear cone to allow it to brake the gear,if your gear change is better the thicker stickier oil is compensating for the wear,but it could have easily exacerbated it as it might on another box,for how long is the question ,Thanks James, I guess that's the only reason I'm actually noticing any difference is that they are worn. Would you feel happy putting this in your own g/box?
id never normally put an ep oil in a gear box not designed to use it, baulk rings are easily damaged as they are designed to move just enough oil from gear cone to allow it to brake the gear,if your gear change is better the thicker stickier oil is compensating for the wear,but it could have easily exacerbated it as it might on another box,for how long is the question ,