2006 Gen2: Oil Consumption Almost Completely Reduced

I have 2004 Prius with 222,800 miles on it (bought from previous owner at 219,191). I switched from the Jiffy Lube special oil the previous owner was using to Mobil 1 High Mileage 5W-30 (available at Walmart) at 220,300. After the first 1,000 miles I noted that the car consumed about 1/2 quart. I added 1/2 quart back in to get it at the "max" line on the dipstick. Another 1,000 miles passed, it was down 3/8 quart. The oil has been in there 2,500 miles now and it has been 500 miles since I checked it last. It is down 1/8 quart. I am noticing a good trend here, could it be the detergents in the oil are making a different? Who knows. I am seeing the difference in consumption. Let's see if it progresses, I will report more later.

Do I mess up my "good oil" only experiment and do the Seafoam or MMO treatment?

 

The high mileage oil has chemicals in it that (among other things) swell seals and it might have a better detergent package. You will not be able to go back to non-high-mileage oil (whether that is dino or synthetic) now that you've started using a 'high mileage' formulation.

It is the 'high mileage' formulation that is giving you the results you're seeing. That is what it is supposed to do. It should only be used on engines that consume high amounts of oil, not on engines that have high miles but do not consume oil.

BTW, what was special about the Jiffy Lube oil?