Gearbox Flush (six speed)
Does anyone have any thoughts on this? I pulled my gearbox (V6 6-speed) dipstick the other day and the oil looks really thick and filthy (it was hard to clean it off of the dipstick, which remains stained or corroded) and the box would appear to have been overfilled. I'm going to change the oil, but as it looked so mucky, I'd like to flush the box. As far as I know, there is no proprietary gearbox flushing product, so I was considering mixing a can of engine flush (about 1/2 litre) with 1 1/2 litres of ATF, filling the box with that (after draining it) and then running it for a few minutes on stands, while running through the box.
Does this sound like a plan? Or is it a Very Bad Idea? If so, any other suggestions?
By the way, the box has slightly weak third and fourth gear synchromesh and sometimes is difficult to get out of gear after I run it to stationery in fourth, declutched. I don't know if a lube change would help with any of this, but I don't suppose it could hurt.