Why is the oil capacity more than twice larger what's needed to raise the level between low and full

Because "low" means the lowest level the oil should ever be. It provides a safety margin so that the motor never runs without adequate lubrication. If it meant "empty", as in out of oil, there would be no safety margin at all.

 

I was trying to figure out what in the world he meant Just keep it full my friend check it every couple of days I mean isn't that what people generally do just because especially when you're talking 20-year-old near classic cars lift the hood in the morning before you start out every so often pull the stick you just have to look at it's been sitting all night no wiping no nothing look at your two red jugs drop the hood and go

 

Interesting, my impression was always the dot between high and low on a dipstick is equivalent to 1 quart of oil, guess not. As for how "lowest level the oil should ever be" Most Gen2 owners that don't check their oil despite my unending pleading get two quarts low and get a oil pressure red triangle going around corners or when braking hard and eventually engine misfire codes attributed to crankcase bearings not having enough oil. Makes me shake my head! None of these vehicles I've worked on had engine damage, but at first once they had oil, they didn't run very well for 20 or 30 miles, then things went back to normal. No doubt shortening the lifespan of the engine.

 

Oil sloshes when you turn corners, accelerate or brake. They have to account for some of the oil being unavailable in some circumstances, even though when the car idles at rest there's a large safety margin as noted by pasadena_commut.

 

If your oil level's at the low mark, and you add 1.5 liters of oil, it'll be at the full mark. Am I missing something?

 

i think he wants to know why the total capacity is more than double the amount needed to go from the low mark on the dipstick to the high mark.
my answer would be, 'why wouldn't it be?'

 

Ah...

 

Well, minor point, there are no 1.5 liter containers of oil. Not a problem at home, just put the extra on a shelf in the garage, but I don't normally carry partially used oil bottles in the vehicle. Too much chance of spilling oil inside.

Also 1.5 liters is an odd amount, most cars are close to 1 quart low to high on dipstick. After a bit of web searching it seems that Toyota is the odd man out here, with a larger dipstick range than other manufacturers.

 

At least for gen 3, the distance between the two marks is also about 1.5", so just eyeballing thirds of that works well. Gen 2 may be similar.

 

I find there's just room to wedge one in down next to the spare tire under the deck boards and cargo tray.

So far (knocks convenient wooden object) my engine doesn't use any noticeable amount between changes, so I don't need the bottle in back.

But, of course, if I didn't have it, I would.