switching to 10w30??

At operating temperature 10w-30 and 5w-30 are just as thick. Beginning part 5w, 10w (or 0w) describes the thickness when cold. End part -30, -40 (or -20) describes the thickness when hot. In both of them bigger number means thicker. Hot and cold aren't in same scale so it's not actually thicker when hot.

So just hot weather is not a reason to move from 5w-30 to 10w-30. They are the same thickness when hot. If for some reason you would need thicker oil options would be 5w-40 or 10w-40.

How much oil is it consuming? Is that really enough to be thinking about stuff like this?

 

If I ever get one of my engines to it's end of life, where it's consuming more than a quart every 1k miles, I'm just going to go right to the top of the common spectrum and do 20w-50. Depending on how it does, I'll start mixing in 90 weight gear oil. Just to see what happens.

 

I have a 2006 Gen2 Prius with 211k miles. At first oil change, I switched to Shell Rotella 10W-30 which worked OK. Subsequently, I have switched to Shell Rotella 40W (from TSC). 40W seems to slow oil usage and I even may have gotten a small mpg boost (say 3/10 to 1/2 mpg). Just my two cents ("$0.02").

PS 40W seems to reduce blow-by. With 40W, I get less spoils in my after-market catch can than with 5W30 or 10W30. My theory is that the 40W reduces blow-by. Blow-by is what propels the spoils from the PCV valve into the catch can.

 

You do realize that 40W will be a lot thicker when cold, so you are making it more difficult to get the oil to where it needs to be on start-up. Start-up is when most damage is done and why the first number on newer oils is smaller - 0W and 5W for example. As Valde has pointed out, if you want to experiment with thicker oils you should be increasing the second number which is the hot weight.

Have you tried either 10W-40 or 20W-50? These would be superior choices in my book.

 

Quart per 1K miles is bad but not horrible. You could try something like 10w-40 to see if that makes it better (or worse) next time you do an oil change. Before that you will know the oil consumption rate more accurate anyways. Wait for at least entire oil change interval before coming to a conclusion about change in oil consumption rate.

Oil leaks need to be fixed anyways. But make sure the leak is actually coming from front cover seam before doing anything about it. Sometimes valve cover gasket leaks look like front cover leaks.

 

Mobile 1 sells a 5 qt jug of 0w40 for $25 at Walmart. 0w40 might just be the perfect oil for these old 1.5 engines. Easy start up, but thicker oil and better protection at operating temperatures.

 

Most recent oil change after almost 4500 miles (a little more miles than I normally shoot for) revealed that my Gen2 consumed about 1/2 quart in the almost 4500 mile interval. For the prior oil change (and current oil change), I used Shell Rotella 15W-40 T4 (I believe that this is Shell's designation for synthetic oil). Additionally, there were no spoils in my after-market oil catch can. My Gen2 continues to provide gas mileage in the 48 to 51 mpg range.

Conclusion: My Gen2's 1.5l motor continues to consume oil but oil consumption has now been reduced to 1/2 quart of oil consumption for almost 4500 miles (about 1/3 of the oil consumption rate when compared with the rate occurring when I first acquired my Gen2).

 

It is T6. And now they have a T6 formula for cars too.

The original was for diesels but worked fine for cars and motorcycles.

I don't know what the difference is with the new stuff but assume that there is no zinc (for cat converters) and a bit of moly for decreased friction.

 

Listen to Aaron.

I have been running 40 weight Redline oil for about 2 years no mileage hit and it stopped the minor oil loss i was starting to see.

Run that M1 0-40. Good buy great oil Go 5000 oci or until the oil on the dipstick really starts to stink of fuel.