Engine Oil Flush...Any Harm?

Don't waste your time or money, and don't risk your engine. If you've been changing every 5k since the car was new with Mobil 1, I guarantee there won't be anything in there to flush out.

 

Well since you asked..... I think it's a complete waste of time. The Prius has the cleanest running engine and oil for any car that I've owned. If your changing your oil at 5k and using Mobile 1 to boot I bet the oil is almost as clean when you drain it as when you put it in. A can of Chevron Techron in your gas every now and then is ok but even that's probably not needed, but I wouldn't screw around with the engine doing a flush....If it ain't broke don't fix it.

 

An "oil flush" does no good. Still, everyone needs a hobby.... Fuel treatments are another waste of money. Use E10 regularly and the injectors and valves will get all the cleaning they need.

 

No flush in fact extend your change out to 10K with Mobil 1.
I run the same as you and change every 10K. But I change out just the filter with an oem filter every 5K.

If you want to be nice to your car change the cvt fluid. Your due.

 

My 2004 is at 187,000 miles and I am still changing syn oil every 5k miles

I am part of a group that has been doing lab testing of our used Type WS Toyota ATF. Mine has been changed every 60k miles and testing showed that the first batch was used up. The ones at 120k and 180k miles have tested successively cleaner (most likely due to the gears "lapping in"). We now suggest that the best protocol for extending the life of a Prius Tranny is to do a first ATF refresh at 30k miles (although at 50k you are still alright) and then each 60k miles thereafter.

My dealer in CT charges me $100 for the job.

There are instructions in an older thread of this discussion group. It is a reasonable DIY job, but you have to go to the dealer for a gallon of type WS ATF and two gaskets for the fill and drain bolts.

JeffD

 

The transaxle ATF fill plug is located on the side of the transaxle that faces the radiator. You will need to raise up the car on jackstands, then put your head under the car so that you can look up in the space between the radiator and the transaxle. Use a trouble light or flashlight if necessary.

The fill plug requires a 24 mm socket. The drain plug is on the bottom of the transaxle and requires a 10 mm hex key socket. Do not confuse this drain plug with a nearby drain plug which is for the inverter and transaxle coolant. That plug requires a 24 mm socket.

 

I have a plastic transmission oil funnel with an add-on flexible hose, for a total length of 3 feet from top of the funnel to bottom of the hose. The outside diameter of the hose might be 1/2" or so, I don't know for sure.

I suggest that you obtain a similar funnel. If you use an attached hose, it needs to fit snugly to the funnel. I use electrician's tape to hold the hose tightly in place.

The car does not have to be level, and adding 4 US quarts is good.

 

Hi Aaron. Out of all the DIY's you could think of that one would have to be the biggest waste of time and money and more likely to do harm than any good. Absolutely pointless given that you're feeding it Mobil-1 every 5k miles.

Re the ATF change, that's a much better idea. I just did mine about 2 weeks ago at about 62000 miles. I used info I found on this site (there's a thread somewhere with pictures) to help me locate the correct drain and filler holes and it was definitely a pretty easy job. I guess it took me about an hour in total, but about half of that was preparation.

 

This post might help.

http://priuschat.com/forums/gen-ii-...roubleshooting/66251-just-drained-my-cvt.html

 

The 2001-2003 Prius uses Type IV ATF and needs the shorter interval (sugessted is 15k then each 30k thereafter. The pan needs to be dropped and cleaned in this earlier model.), but from our testing of 2004-2005 Prii, the 30k, 60k, 60k, ... protocol looks good (You can extend the later refills to a somewhat longer interval if desired).

JeffD

 

Ramps work, just recently did mine on ramps. Stick some wedges behind the back tires tho for safety. I felt it might be a little inaccurate to check the fill level with the front lifted but it's probably not an issue. I rolled off the ramps and then stuck my finger up there with the car level just to recheck, wasn't easy!
Some of us just enjoy doing these things ourselves, but it's not quite as simple as an oil change.

- D

 

Draining was OK. But when filling, with the fill hole up front, I just had the sense that it would tip the level too low away from the hole. (This is the kind of anal silliness that makes DIYers not want to leave it to the pros!)
It didn't take the whole 4 quarts in my case, I have about 8oz still in the last bottle.

- D

 

Yeah that's the idea of having the filler hole on the side like that. When it starts draining back out the hole as you're filling then you know it's full.