So although I did not have any reason to think I lost any fluid, I decided I should check the level of the automatic transmission in my 1999 Blazer and when I did it, after having driven over 20 miles, parked on a level spot, and with the engine running and in Park, I saw that the fluid was high. It was about one to two widths of the hashed range on the dipstick higher but it was no foaming.

This concerned me so I called up the transmission shop this morning to ask them about it and according to them for my Blazer the proper way to check the level is when the transmission is in Drive. The guy explained that the instructions in our owners manuals say to do it in Park so that no one gets run over and can then sue GM.

Anyone have any other thoughts on this?

 

Someone is full of it!! It might be a bit overfull by 8-16 oz. not to worry as the transmission will send what it doesn’t need out the breather and leave a mess under the vehicle.
Brad

 

That's the most dangerous and stupid thing. I would never step in front of a vehicle that's in drive, unless it's on jack stands and wheeless... I've always checked trans fluid while it's hot, but I have noticed that our dip sticks also have a notch for cold temps.

 

In drive? That doesn't make any sense

 

The dipstick lands into a sump tank. As far, as the engine is running, the torque converter rotates.Its output is hard linked with the transmission oil pump. The oil pump creates the oil flow within the transmission assembly. Depending on gear selector position it just moves the pistons engaging clutch packs here and there. In my opinion, there is no difference what gear are You in.

How do they explain their "driven" theory?

 

EDIT:
On second thought, I think I should be more specific here. The engine flywheel is mechanically connected with the torque converter chassis on one side. On the other side, the chassis drives a transmission oil pump vane ring. So the transmission fluid pump is hard linked with the engine crankshaft output. It doesn't matter whether You selected any particular gear.