What oil do i use in the pump? The oil is milky and needs changing.

Per owners manual... WATER PUMP OIL IMPORTANT: If oil is white or foaming, water is in the oil reservoir. Change oil.NOTE: Water in oil occurs as a result of spray or condensation. Milky oil is not indicative of a pump malfunction.

Milky appearance in oil is due to water mixing with the lubricant. An internal seal has failed. Have your pressure washer checked by a small-engine mechanic immediately.

You have a blown head gasket ! The milky looking oil is coolant getting in there ! Mite smell like gas because some of that is getting in there also ! It over heated ,warped a cylinder head ! Milky oil How to tell if your oil is milky

Hi Derek.
It is almost impossible for the engine oil to become "milky" under normal circumstances. If you have changed the oil and have used the wrong type, it may become aerated and appear milky. The only other way for water to be added to the sump is through the oil filler. I doubt this is the case as it is a neglect thing and indicates that someone has run the machine without the oil filler caps. Hopefully this is not the case, but as the engine has a low oil level sensor, it might be the reason why it wont start. It's a safety device.
There is no way that the engine oil can be contaminated by water from the pressure pump.
If you mean that the water pump oil is milky, this means that the seals have failed between the pump and the transmission. Difficult to check in a G2500. If this is the case the machine has probably been used beyond the manufacturer's intent and has overheated.

have a coolant system pressure test done as there may be corrosion behind the water pump impellor that is letting water out into the sump. Check all aluminium fittings that connect to the oil system for corrosion

The better thing would be to change the oil and filter now. Why wait to lessen the problem. Yes, it is water that is turning the oil a milky color. The real question is whether the water is just condensation or is it a water leak at the internal water pump. I'll bet this is the first time you ever prayed for condensation. Best wishes. Please rate my answer. Thanks.

it may have a slow water leak inside the pump.
change oil and monitor the new oil.
if it goes milky the next time you use it then it has a bad leak and the seals will need to be
replaced,otherwise the bearings will rust & seize

If water gets inside the gearbox, it will emulsify due to the "blending" caused by the gears and crankshaft. It turns the oil a milky color. The water can come from a bad oil seal on the water pump (if the bike is water cooled), or from condensation inside the gearbox. Sitting out in the rain, pressure washing or riding in creek beds can also be the water source. Find the water source and fix the seal or otherwise remedy the exposure. You will need to do an oil change. Please rate my answer. Thanks.

milky appearance means water is in the pump oil.......sounds like your spill valve is sticking and needs maintenance

your water pump seal and oil seal have failed on the water pump shaft. Replace both seals noting which way the seals face. replace the water pump shaft if it is scored. Chaz- Moto DC