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Why not have drain plug at the lowest place on the pan?
March 03, 2023, 04:04 PM
ridewvWhy not have drain plug at the lowest place on the pan?
Changing oil in my Corolla I noticed that for no apparent reason they have the drain plug located in one of the raised areas of the oil pan rather than on one of the lower ones. Is there a good reason why the pan is designed like this? I've noticed similar on other vehicles as well.
No car is as much fun to drive, as any motorcycle is to ride.
March 03, 2023, 04:10 PM
arfmelPossibly to protect it from being damaged when somebody hops a curb?
March 03, 2023, 04:10 PM
kkinaProbably to protect the plug from bottom scraping on road hazards. (Arfmel a split second faster on the return button)
March 03, 2023, 04:23 PM
NavyGuy^^^^
And that little bit of oil that's left over is not an issue since you're adding 5-6 quarts to dilute it.
I used to agonize about trying to every single drop of old oil out, to the point I used to let it drain overnight, and even refilled with some cheap oil, drove it for 10 miles or so and then drained it overnight again. God was I stupid.
Men fight for liberty and win it with hard knocks. Their children, brought up easy, let it slip away again, poor fools. And their grandchildren are once more slaves.
-D.H. Lawrence March 03, 2023, 04:24 PM
ridewvI don't believe that's the reason because it's well up, also with a cover underneath that was removed to access the plug so not shown in the pic.
No car is as much fun to drive, as any motorcycle is to ride.
March 03, 2023, 04:32 PM
ridewvquote:
Originally posted by NavyGuy:
And that little bit of oil that's left over is not an issue since you're adding 5-6 quarts to dilute it....
I bet there was a good 1/2 quart laying in the bottom of this pan, so of 5 quarts 10% of the dirtiest oil in the bottom of the pan remains. But you're right in the whole scheme that doesn't make much difference, it just would seem to be good practice to have the plug at the lowest point, as long as it's not vulnerable of course.
No car is as much fun to drive, as any motorcycle is to ride.
March 03, 2023, 04:34 PM
architectProbably for clearance Clarence, either to clear a splash guard, or maybe (unlikely) to spare the poor mechanic's knuckles, I say "unlikely" because what design engineer ever cared about that?
Bersides, does't everybody vacuum the old oil out through the dipstick hole these days? Crawling under the car is so last century.
March 03, 2023, 05:02 PM
ridewvHell vacuuming it out would probably leave even more sludge. The filter needs changed too and it's right there about 8" from the plug so I'm there anyway.
I suppose on your car where you suck the oil out of the dipstick tube, the filter is up there too. That would be convenient.
No car is as much fun to drive, as any motorcycle is to ride.
March 03, 2023, 05:13 PM
trapper189At least you don’t have to jack the back end of the car up to drain the oil. My dad has a car with a flat oil pan and the drain plug is in the front. You pull the front onto ramps and jack the back up higher to get it to drain.
March 03, 2023, 05:30 PM
egregoreToyota
trucks (4Runner, Tacoma, and I think the Tundra) do have the plug directly in the bottom of the pan … as they should be. I don't care much for leaving up to a half a quart of still-dirty oil in the engine, myself. I have changed the oil on schedule on my own Corolla since new, so it isn't much of a problem for me, but not everyone maintains their cars like we do.
March 03, 2023, 05:43 PM
sigspecopsOn a lot of vehicles, the plug is at the back of the pan, about an inch or more above the bottom. There's quite a bit of old oil left behind. On the trucks I've had, it wouldn't affect clearance at all if it were on the bottom.
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March 03, 2023, 06:53 PM
6gunsI'm with you, ride; that would piss me off.
I'm happy to say the plug on my Honda CR-V is at the rear/back of the pan. When on ramps, I'm getting ALL the old oil out!
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March 03, 2023, 06:55 PM
Rey HRHquote:
Originally posted by NavyGuy:
^^^^
And that little bit of oil that's left over is not an issue since you're adding 5-6 quarts to dilute it.
I used to agonize about trying to every single drop of old oil out, to the point I used to let it drain overnight, and even refilled with some cheap oil, drove it for 10 miles or so and then drained it overnight again. God was I stupid.
Wow. That's some due diligence!
"It did not really matter what we expected from life, but rather what life expected from us. We needed to stop asking about the meaning of life, and instead to think of ourselves as those who were being questioned by life – daily and hourly. Our answer must consist not in talk and meditation, but in right action and in right conduct. Life ultimately means taking the responsibility to find the right answer to its problems and to fulfill the tasks which it constantly sets for each individual." Viktor Frankl, Man's Search for Meaning, 1946.
March 03, 2023, 08:17 PM
ridewvYes on some vehicles like, I believe the Ridgeline, the bottom of the pan is flat and the plug is on the rear with the bottom threads right at the bottom so everything drains.
No car is as much fun to drive, as any motorcycle is to ride.
March 03, 2023, 08:22 PM
hrcjonno idea, but you can bet some engineer spent 20,000 hours to figure out the optimum position given all the variables (you know its not just getting the oil out, its the stamping design, its welding the other side of the drain plug, its impact on the windage baffles, access, etc. etc.) And of course it makes absolutely no difference in the scheme of oil life. Like none. or less than none.
“So in war, the way is to avoid what is strong, and strike at what is weak.”
March 03, 2023, 08:24 PM
PykerOn my truck (RAM 1500) and car (Explorer), I put them up on ramps, drain the oil and change the filter (both drains are at the rear of the pan), then refill them with the stated amount of new oil and roll them off the ramps before I check the level.
If they were recessed into the center, as in the OP, that would be a massive pain in the ass.
March 03, 2023, 09:12 PM
ridewvOn some vehicles I've had refilling with the amount listed overfills the sump but Toyota did seem to get the refill amount correct. They call for 4.9 qts with filter. I added 4.5, lowered it off the ramps and checked the level and it was about 1/2 way between add and full, so dumped in the remaining .5 qt and it's right at the full line.
No car is as much fun to drive, as any motorcycle is to ride.
March 04, 2023, 05:34 AM
sourdough44One beef is a plastic cover over the area(aerodynamics?) that has to be removed to access the plug(CR-V). I leave it off since it’s a HWY vehicle.
I try to park on our sloped driveway to get the best drain, a little helps. Beyond that I’m in the dilution camp, no biggie.
I also don’t like lack of a drain nut on differentials and transmissions.
March 04, 2023, 05:46 AM
erj_pilotIt’s in the rcessed part of the pan so that the plug is out of the wind stream when driving, and therefore reduces induced drag for better speed.
"If you’re a leader, you lead the way. Not just on the easy ones; you take the tough ones too…” – MAJ Richard D. Winters (1918-2011), E Company, 2nd Battalion, 506th Parachute Infantry Regiment, 101st Airborne
"Woe to those who call evil good, and good evil... Therefore, as tongues of fire lick up straw and as dry grass sinks down in the flames, so their roots will decay and their flowers blow away like dust; for they have rejected the law of the Lord Almighty and spurned the word of the Holy One of Israel." - Isaiah 5:20,24 March 04, 2023, 06:48 AM
trapper189Hey man, don’t laugh. Every 1/1000 of a MPG counts when multiplied by the number of vehicles Toyota manufactures.