My Sienna appears to have lost something like half a quart of coolant, in the past 5000 plus miles (a period of about 6-7 months). I filled it up to just above the full mark earlier this year, and went out last week and had to fill it up some more. It was about halfway between the low and full marks. I just looked now, and a guesstimate would put about a full quart in between the low and full lines. The manual didn’t give any indication of how much that distance would be. My question is—does coolant burn up at all? Or if the level drops, does it simply leech into the oil? I’m thinking about the effect of this coolant if in fact it did get into the oil. Its probably not providing good lubrication for my engine. After filling it to just over the full mark earlier this year, I noticed a blotch of pink goo on my driveway about where the engine is, so I know a small amount of it came out of the overflow tank, but that is the only time I’ve seen that, so this last half quart didn’t just bubble out.