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Hello again. Can anyone help me understand how I can remove all the oil from the transmission on my. 89 V12 please. I've read that the torque converter holds 60% of the oil in the gearbox and won't drain simply by removing the pan. I hear suggestion of using an oil suction pump.. Not clear on how it's done. Can anyone offer any help please.

Hi Sam - one approach is to repeatedly change the fluid until you have diluted the old fluid down to a very low proportion. For example, using your figure of only changing 40% at a time so 60% of the old fluid is left, by the time you've done the change 6 times you will have less than 5% of your old fluid left. If you have the patience to do it 10 times you will have less than 1% of your old fluid left.

the only way for 100% fluid removal , is to remove the grearbox and strip it down , and even then the torque converter needs cutting open

as David says, a running oil change with multiple efforts will remove most, but not everything,

if the gearbox is in ' good ' condition , 100% drain is not required, if the box has a fault, it needs removing anyway

search my posts for my GM400 removal , refurb , rebuild and reinstall into my V12 XJS

BB

Cheers gents, will just drop whats there then. Do I need to cycle the gears when refilling when running or with the engine off, please? There's a leak on it somewhere. Only seems to drop on the garage floor on startup and no more than an eggcup full .. less in fact.

Refill to the max mark on the cold side of the dipstick. Then, start the car, let it idle and move the gear lever several times through each of its positions. Check the dipstick readings and top up to the full mark on the dipstick (cold) still with the engine running. Finally, take the car for a run (min 20 miles) and check/top up to the max mark on the hot side of the dipstick. Mike.