Definitive, sourced info for oil overfill affecting MPG? - Page 2 - Toyota Prius Forum : Prius Online Toyota Forums
User Tag List

Reply
 
LinkBack Thread Tools
post #11 of 18 (permalink) Old 08-25-2006, 08:50 PM
Super Moderator
 
Join Date: Feb 2005
Location: Eastern Washington State
Posts: 887
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

The problem that we have with oil "overfill" is not the fact that the sump is overfilled, because a 4qt fill is not a problem. The problem is Toyota converting Metric straight over to English without taking into consideration that the english system of measurement is not decimalized. Which means that anytime you do a conversion between Metric and English you end up with fractional differences between what otherwise should be even fluid fills that have to be represented by decimals.

Toyota should have looked at how the US market purchases oil. They would have determined that writing the books to indicate that an even 4qt fill would be easy to acomplish for any grease monkey or shop and reduce confusion among owners. This fractional sump volume has been a thorn in the side of dealerships and owners since day 1. Over the past 19 months of ownership I have had 4 oil changes, all of them a full 4 qt fill. And the drop in FE I have seen has been negligable and has only affected the tank in which the oil change occured. I attribute this to the supid procedure of revving up the enging after doing an oil change by some oil change places, and other places that do a short test drive after the oil change is done. In other words, it isn't oil quantity, it is the driving habits of those that have the vehcile when it is not in my hands.

I would really like it if somebody who aserts that a 4qt fill on an oil change drops FE would detail how a .10 of a quart is affecting their FE. I've heard crank slap as an issue, and yet a cross section of the engine indicates that the crank is many inches above the highest point of a 4qt fill. In fact I would estimate that it would take 5qt+ for crank slap to occur and that would cause severe driveability issues and the driver would notice it immediately. Beyond crank slap, I can't think of anything else.

Drag on oil pump? No. Because the oil pump intake is always pulling oil from the lowest part of the sump and the pump can only take in so much oil at any given time based on the size of the intake and the volume of oil that the pump can move per revolution of the pump mechanism. In other words, the operation of the pump is totally unlrealted to the sump level.

My creative juices are not running well right now, but suffice it to say, I can't think of anything that a minor "overfill" would do to cause any change in MPG.

The jury is still out, but I don't think they are going to come back in and post a verdict.

It has been said:
Hybrid drivers come in 3 flavors, greenie, techie and cheapie. Pick any 2.
2005 Prius, Millenium Silver Metallic (color code 1C0) over gray, package 5 (AI)
jeromep is offline  
Sponsored Links
Advertisement
 
post #12 of 18 (permalink) Old 08-25-2006, 08:58 PM
Senior Member
 
Join Date: Aug 2004
Location: Tampa Bay
Posts: 7,166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Send a message via AIM to DanMan32 Send a message via MSN to DanMan32
Default

First off, even at 3.9 quarts, you are still over the full mark of the dipstick. 3.5 quarts puts it just right.

Second, where do you find a cross sectional view of 4 quart fill in relation to the bottom of the crankshaft? Do you actually have a clear plastic oil pan? Or maybe transparent aluminum.

I would agree though that we really don't know without being able to see where the fill line is and how close the crankshaft becomes. Our tests and suspicions admittedly aren't scientific.

But the crankshaft doesn't have to actually hit the oil level to cause drag, since oil is a fluid and will be affected by the motion of something just above it.
DanMan32 is offline  
post #13 of 18 (permalink) Old 08-26-2006, 12:06 AM
Senior Member
 
Join Date: Apr 2004
Location: Cape Cod, Massachusetts
Posts: 4,878
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

And who knows who put the dot on the dipstick? I know it was me who notched mine at the four qt. mark.



hyperion is offline  
 
post #14 of 18 (permalink) Old 08-26-2006, 02:45 PM Thread Starter
Super Moderator
 
Join Date: Jul 2005
Posts: 640
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Default

Quote:
Originally Posted by DanMan32
First off, even at 3.9 quarts, you are still over the full mark of the dipstick. 3.5 quarts puts it just right.
This statement would contradict the owner's manual stating that full is 3.9 qts., including the filter. According to that, 3.9 should be on the fill mark. If what you say is true, Dan, then I actually have about 3.8 qts., being .3 above the fill line. Whatever, I'm taking my car in on Tues. to have the wheels balanced and while there, they will drain it to the fill line.
wayneswhirld is offline  
post #15 of 18 (permalink) Old 08-26-2006, 03:28 PM
Senior Member
 
firepa63's Avatar
 
Join Date: Jun 2004
Posts: 2,243
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Default

Quote:
Originally Posted by wayneswhirld
Quote:
Originally Posted by DanMan32
First off, even at 3.9 quarts, you are still over the full mark of the dipstick. 3.5 quarts puts it just right.
This statement would contradict the owner's manual stating that full is 3.9 qts., including the filter. According to that, 3.9 should be on the fill mark. If what you say is true, Dan, then I actually have about 3.8 qts., being .3 above the fill line. Whatever, I'm taking my car in on Tues. to have the wheels balanced and while there, they will drain it to the fill line.
The reason 3.5 quarts is about the right amount is that you can never get all of the oil to drain out. If the sump was completely dry, 3.9 quarts would be the correct amount.
firepa63 is offline  
post #16 of 18 (permalink) Old 08-26-2006, 03:48 PM
Senior Member
 
Join Date: Apr 2004
Location: Cape Cod, Massachusetts
Posts: 4,878
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

But you got to ask yourself if a little more is better than a little less. And whats the pain in the butt worth in that ever seeking 3.9?



hyperion is offline  
post #17 of 18 (permalink) Old 08-26-2006, 07:54 PM
Senior Member
 
Join Date: Aug 2004
Location: Tampa Bay
Posts: 7,166
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Send a message via AIM to DanMan32 Send a message via MSN to DanMan32
Default

I do know that I removed 1/4 quart of oil after a fill, and it ended up right at the full mark.
DanMan32 is offline  
post #18 of 18 (permalink) Old 08-26-2006, 10:06 PM
Senior Member
 
Join Date: Apr 2004
Location: Cape Cod, Massachusetts
Posts: 4,878
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Default

What a pain in the butt that must have been! (I would guess then that the "full" marks put on the dipstick by Toyota are not at the 3.9 position?)
I wonder why they chose to mark the dipstick at 3.75?
One other observation: 4 qts of oil is much closer to the 3.9 full quantity specified as "full" by Toyota than is 3.75.



hyperion is offline  
Reply

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



  Similar Threads
Thread Thread Starter Forum Replies Last Post
Gas overfill & spill Terry Pallone Toyota Prius Technical - Q & A 5 03-04-2009 08:57 AM
Common to overfill oil? spitsnrovers Toyota Prius Technical - Q & A 13 04-06-2007 07:36 AM
anything definitive on the 2008 Prius? Titanicman Toyota Prius General Discussion 20 01-11-2007 12:09 AM
Oil Overfill Damage Yarok Toyota Prius - Technical Chat 7 04-22-2005 09:31 AM
What is the definitive answer re 'larger than oem' wheels Richard Cook Toyota Prius - Technical Chat 4 05-28-2004 03:37 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome