On sort of a whim last night, I changed my oil for the first time. I was going to do it this weekend but then decided, might as well get it over with now. One thing I didn't do was replace the oil plug gasket. One was included with the filter cartridge, along with the oil filter O-ring, but it appeared that the original gasket was kind of stuck to the outside of the oil pan (i.e., it wasn't around the oil plug and it didn't fall into the pan I drained the old oil into - I fished around to be sure). I tried to pry it loose from the oil pan but it wouldn't come off. So I just screwed the oil plug back in and called it a day. My question is, should I now go to the effort of draining the new oil into a very clean pan, so that I can install the new gasket? I didn't think this was very important at the time, but several threads here say "remember to install the new oil plug gasket!" so maybe it is. What's the worst that can happen if I don't do this? What are the chances I'll develop a leak at the plug? And a follow-up question: is 4 quarts sufficient or should I add another 0.4 quart? The instructions I used, I think from Bill somebody, were printed from this site almost a year ago and they called for exactly 4 quarts. But now I see that apparently the owner's manual says 4.4 quarts should be added. Thanks.
No, those gaskets can last at least two changes (according to my service dept). The level of the oil is important, not how much. Make sure the level is between the two dots on the dipstick.
I changed my oil and filter about two weeks ago and added 4 quarts. After driving around for a couple of hours, the oil level was about 3/4 of the way between the low and high dimples. Two weeks later and several hundred miles it is still 3/4 between the dimples. I will continue to monitor but do not plan to add any at this time.
4 qts is enough since less than perfect complete drain. But go by the stick, ultimately. Washer should be ok. I have re used them too. You can tap on a screwdriver very carefully so as not to scratch the pan and knock the old washer loose. Certainly replace it next time. And watch for any drips or change in oil level from time to time during this interval.
I agree with the above posts, too, that you should be fine. With the Prius all "buttoned up" underneath, you can't easily get under to see if your drain plug is dripping. So, as you're experiencing, it's cheap piece of mind to replace the drain plug gasket, and if you're really OCD, use a torque wrench to tighten the plug. Also, you may want to try a putty knife, or old spatula, when removing the drain plug gasket next time. Screwdrivers can slip (don't ask me how I know).
Since you've just added new oil, I would say that you should leave well enough alone. If you don't see any oil spots where you park, then no worries. For the next oil change, while the drain plug is loosened but still in place, if you tap gently on the washer's edge using a flat-blade screwdriver and a small hammer, the washer will come free and rest on the drain plug. Avoid scratching or gouging the oil pan's surface. Then you can remove the plug and washer, allowing the old oil to drain out.
Next time, you might consider replacing the drain plug with a Fumoto valve (FUMOTO ENGINEERING) so you wouldn't have to worry about it again.
We have 45,000 miles on our Prius. I do all my own oil changes with factory oil filter and Mobil One 0w20 oil. When I change the oil and filter I pour in exactly 4 quarts of oil. I change every 10,000 miles. The oil is alway within the two dots, and when I change the oil nearly 4 quarts drains out. I believe 4 quarts is enough any more is probably not necessary. just my opinion alfon
