Which oil to use? "0w-20" vs "5-w20" vs "0w-20 high mileage"

Isn't a 2006 Prius suppose to take 5W30 oil?

To answer your questions 0w20 is thinner than 5w20, when cold. They both are suppose to shift to 20 weight when hot. The 0w20 high mileage is supposed to meet uniform specifications but individualized testing seems to indicate that it's slightly thicker and has more wear prevention additives in it.

Hope this helps.....

 

a heavier oil may help some. As mentioned, at least stick with the weight on the fill cap (and owners manual), 5W30. “high mileage” oils basically have extra additives that swell seals, in particular the seals on the valve stems.

Taking out the spark plugs and putting in a solvent you “may” be able to loosen piston ring deposits.

ultimately you’d need to either rebuild the pistons with new rings, or a new short block (the portion of engine between upper oil pan and head gasket), plus a machine shop go-over of the head, with new valve seals.

Get the complete gasket kit and head bolts. Toyota has both, and probably best bet. The gasket kit includes a new head bolts.

 

IMHO, it doesn't really. You don't have to take my word for it, track your mileage when you use 0w20. You better keep an eye on your oil level, going thinner than OEM recommendations will likely cause more oil burn - coating the CAT, leading to expensive repairs down the road to save pennies now.
If your not in snow country, I'd move back to 5w30 or 10w30 to prevent the oil burn to avoid an expensive CAT replacement, down the road.

It's your car, experiment with it....

 

High mileage oil "might" help, if the consumption's due to leakage past the valve stem guides/seals. Once you start on it, best to stick with it. If you return to regular oil apparently the guides/seals can shrink back, be worse.

 

Quality matters, especially with newer, tighter tolerance equipment. Same goes for motor oil.

I inherited my dad's old Toyota SR5 pickup. It required some work to get it back to 100%, mechanically. When I was driving it home, I noticed it had a low oil pressure issue when hot and idling. It was the first gen V6 and had the head gasket recall done on it and 185K miles on the clock. I ordered a full timing belt kit & new radiator, top tank had small holes so leaking coolant to boot. While I was waiting for the parts to arrive, I did basic maintenance on it, spark plug, check the brakes, rotate the tires, oil change. After that the low oil pressure issue when hot and idling went away. Later found out that dad got lazy and took the truck to Jiffy lube for oil changes, it was that cheap drum oil they used that didn't meet specifications when hot. That's probably why they tell their customers to do oil changes every 3000 miles.

Just something to think about when you reach for the cheap, no-name stuff.... Penny-wise, Pound foolish..