2007 prius Oil change Instruction

john1701a has been a great source for basic info. However I noticed that his oil change instructions are updated for the 2010 model year. Therefore I've provided a page out of the repair manual; this is correct for Classic and 2G models.

Note the fluid capacities cited in the repair manual page. If you adhere to those guidelines you will likely find that your crankcase is overfilled based upon the engine oil dipstick.

I suggest that you add 3.7 US qt and then see where the dipstick level is after waiting a few minutes. The oil level should not be higher than the top dimple in the dipstick.

 

Here's a fool proof method to adding oil: Just add exactly 3 quarts. You'll end up right between min and max.

No pouring a bit in, rechecking the dipstick, and then adding a bit more. (also no worries about overfilling and having to drain/refill).

 

That is reasonable.

My personal practice is to use 3.5 qt because I can save the remaining 0.5 qt for use at the next oil change without having to measure again. That refill amount brings the oil level to around 1/4" below the top dimple.

Why doesn't anyone advocate use of just enough engine oil to reach the bottom dimple on the dipstick? That would be a little more than 2 quarts...

This would be a bad idea because your engine would have no safety margin in the event of a leak or if it is worn to the point where it is starting to burn oil. Also, 2 quarts of oil would have to work twice as hard as the rated 3.9 quarts so you'd expect used oil testing to show greater degradation after a given number of miles had elapsed...

 

( With thanks to Patrick Wong just above .... )

Using 3.5 quarts each oil change sounds good to me! I think that's what I'll ask for from now on ... beginning with Mithril's next oil change due the first week in December.

A few days ago, I took "him" in for a windshield treatment ( Aquapel ) and asked them to drain 1/4 of a quart while I was there as the oil level was a lot closer to the full indicator than the fill indicator.

It's way too early to tell if Mithril's MPG might consistently be a bit higher than it has been overall, but many here have reported fairly significant MPG improvement if the oil level is maintained toward the bottom of the range.

All I know for sure is that on the way to the dealership -- primarily south of here / driving into a very light, southerly wind -- the MFD indicated about 51.9 mpg for the 60 mile trip, and for the return trip the MFD indicated about 60.4 mpg.

I'm sure MUCH of that increase was due to the shift in relative wind ... but a 16.5% increase?!? That was WAY more than I'd expected!

 

One of the reasons to use only 3 quarts under warranty is that the oil change interval is too short to begin with. The extra oil of 3.5 or 3.7 is simply wasted. If I extend the interval I might go back to 3.5 quarts, but not more. I like what my mileage has done as I've gone down to 3 quarts...may just be coincidental with break-in periods for car and driver(s).