DO NOT, I repeat DO NOT overfill!

[xaxis360]

Yet another automatic transmission biting the dust I thought... My 93 SE started acting funny. Rough shifts, 1st to 2nd at full throttle now produced a BANG instead of the normal *pause, shift, engage* feeling like it used to. I checked the shift cable, changed the fluid and ... nothing. Then, as I was gazing at my overfilled ABS resevoir, it prompted me to check my ATF dipstick again. When I looked closely, what looked like a topped-off transmission, was actually a grossly overfilled one...by about 3/4 a quart! So, I devised a plan to extract it using an old windex bottle as the siphon and viola! No more problems. I took care of the ABS resevoir as well, then jumped on Honda's "Service Express" to see what I could find...

Honda has seen the overfilled problem before aparantly with engines. My new creto will be halfway between MIN and MAX except engine oil (since it's fluid that is used up.) I have heard some wierd stories about customer's changing their own oil, but that one's a little odd.

[KillerCam282]

Makes plenty of sense. Gross overfill can damage seals, pumps and other moving parts. It pretty much creates an added resistance that some parts were not built for.

[sj960]

And causes aeration, air bubbles in the oil causes it to lose its lubricity.

[F22-GURU]

Not to mention the poor old crankshaft having to slap through all that oil.
A customer of mine kept filling his Toyota Landcruiser engine until his Oil Pressure Gauge read higher. He thought it was like a Fuel Gauge. Because the engine was a little low and noisy he added extra 7.5 Litres of Oil to a Sump already with 7 litres of oil. (Capacity of 8.2L). Result 1 Blown Rear Main Oil Seal.

[wrichards2005]

Too much oil makes the oil sud/bubble up like soap. Thus, it can't lubricate, and leads to engine failure. That would be bad..