I have a 2006 Prius that is at 250k and going up rather quickly. I have a 120 mile round trip commute each day that involves climbing a mountain pass and the little 1.5L engine spends a lot of time at redline on the way up.

The car burns approx 1 qt per 2000 miles, I have tried several different oils from 0-20 to 5-40 diesel oil neither seems to completely stop the oil consumption. A new PCV valve did not help things, it smokes a bit on startup when cold leading me to believe its valve stem seals.

My goal is to reduce running costs as much as possible. I work a lot and dont have much free time to change my own oil. I have been running Dino oil with FRAM ultra synthetic gold filters. I drop the oil at 7000-9000 mile intervals and the last filter I took to 16,000. Just looking for some suggestions as to how I can extend the life of this engine a bit more. The reason I have the long intervals is I think having a weekly oil top-up would constantly be giving the engine fresh oil.

The previous owner always used synthetic up until 150k when it started to consume oil it was switched to Dino. I am mainly looking at this from a cost perspective, this car is a beater and I want to keep it running with minimal oil costs. Here in Canada a jug of synthetic is $30 and Dino can be had for $13. Any suggestions should I switch back to synthetic or stay with Dino?

I would use a conventional mono grade, unless you are in full blown arctic conditions.

I'd just use cheap oil and keep it topped off.

There's your mistake. You want to go 7,000-9,000 on conventional. Toyota's own oil is not even conventional.

Go 5k on SuperTech or Castrol.

If the rings are worn and allow some blow-by to contaminate the oil, it's probably a good idea to change the filter every oil change. If the oil turns black quickly, I would suspect the rings.

keep in mind that at 5k I have already added 2 quarts of fresh oil back into the sump...or about 50%.

I'd just use a synthetic 5w30 and change it every 15k miles or 24k kilometers.

I would change the oil filter EVERY OCI no matter what.

I would just run the ultra to 25-35000km depending on how daring you are and keep adding top up oil. Try to get a pail of something for sale cheap and decant that as you please. When you change the filter dump the oil to try to get any junk out of the pan. I would go as thick an oil as I could due to high rpm use.

I would go with a 5w30 HM synblend that you can pick up on sale and stock up on it. Since you're adding a litre every 2,000 miles go with a long life filter, Fram Ultra and use it to it's max. 20,000 miles.I don't see a need for ever doing a complete oil change. Good luck.

If it were mine I would do 5K oil changes with 5w30 Walmart dino oil and filter. Or whatever is cheapest in your area.

These cars are used for new york taxis and you should be able to get many more miles out of it.

I would take a peek at the plugs after burning that much oil.

I do not know if you are able to get your hands on this in Canada, but I definitely would, in an oil burner. 5 gallon pail of 5w30 synthetic blend oil. What I would do is save a random clean container for "top-up" oil to keep in the vehicle (even a 2L Coke bottle will do), if I am away from garage for a while, and simply refill with oil from 5 gallon pail as needed. This task is super easy with a pump made specifically for these pails.

A few things...

Oil and air filter should be changed per OEM specs... especially if you're to the point where you're getting a bit of blow-by.

The 1.5L thrives on 10k full synthetic oil changes. Just do that and get whatever rebate offers the best discount. Since you're burning a quart every two k I would just top off the oil after every gas fill-up and use that as an opportunity to keep track of the other fluids as well.

That 1.5 Liter is dirt cheap to replace and since you're in Canada, you probably don't have much battery degradation, especially since you drive it so much and so often. I would just keep the fluids fresh and topped off and keep it running on Toyota's maintenance schedul. Chances are the electrical system will go before the engine or tranny need to be replaced.

All the best

Steven Lang

Well first I would not believe what prior owner told you unless you see receipts or he was trusted friend.

Your issue is likely oil control ring crudded up. Consider Kreen or Auto-Rx or piston soak. I doubt valve stem seals are causing all of the oil burning issues. Compresion test?

I would run a synthetic blend (sale oil) at 6000 to 7500 miles. Change the filter every time.

Let's pretend like it is 1960 ... add a can of STP at every change, and a can with each quart of oil added ... <BIG grin>