How much oil really is circulating?

Messages
289
Location
Terra firma
OK I'm gonna fess up now...this is a dumb question but I've got a lot of dumb questions floating around in my head. At any given time how much oil is actually circulating in the engine? For instance, my Explorer holds 5 qts but that amount isn't doing "oil duty" if you know what I mean. Is it a qt, half a qt or 2 qts? Anyone know? Anyone want to venture a guess? Anyone care?
 
Messages
43,676
Location
'Stralia
Smokey used to say that small blocks, even loose ones needed less than 8 gallons per minute. I'd say everything within your engine is circulating 5 or 6 times per minute, some area take longer to return than others.
 

Al

Messages
19,256
Location
Elizabethtown, Pa
Yea-but he wants to know how much oil is in the engine vs. in the pan at any given time. I'll take a wild guess at about 2 quarts-maximum. Probably less. That falls into the catagory of "Wild Guess" [Cheers!]
 
Messages
3,334
Location
Bolivia
It depends a lot on the engine, it's position in the vehicle, and the vehicle's intended use. Take two pickups with the same engine: one 4x2 the other 4x4. The 4x4 normally has 1 to 2 qts more oil knowing that it will go steep angles and shake up the oil. It there is room to put a deep part in the pan, the total can be reduced. If it's designed for long distances, the reserve is also increased.
 
Messages
8,711
Location
Nothern USA
That is an interesting question. I suspect that it takes very little oil at any one time to be doing the work. The amount of oil in the galleries and passageways along with the actual bearing clearances can not be very much. It may be less than the amount of oil in the oil filter. I suspect much of the oil is busy sloshing around the oil pan making sure the oil pick up is covered on turns and acceleration and deceleration. Some of it is there as a reserve too, making sure the oil pick up would still be covered if you were down. A big pan full of oil loses more heat too. There is a good reason why many of the hard working 4 cylinders have finned aluminum oil pans. They have always been use on performance engines. I am not sure how you would tell. I don't know if you can get a good dip stick reading with the engine running. With a good ADBV, the oil level may not be much different than with the engine off. The engines that give a lower reading right after shutting the engine down, may be more a poor ADBV. I guess you could drain the oil down to where you lose oil pressure and see how much is left. I doubt if many of us want to know that badly, even if there is plenty of evidence* that quickly shutting the engine off would prevent any damage. Maybe if you look at how much more oil comes out after you take the filter off on an oil change. Even then, much of the working oil may still stay in the engine. the more I think about this, the harder I think it would be to really find out. *See dealer forgot the oil. http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=24;t=000357;p=2#000060
 
Messages
398
Location
Chicagoland, IL USA
I once borrowed my fathers '92 Ford Aerostar with the 4.0L V-6 to move down to college. This thing leaks some oil and burns a little also, it also has like 15X,XXX miles on it at the time. Anyways, I change the oil the day I leave(just dino Castrol, 10W-40 I think and a Fram filter), and then proceed to head down the highway for the 280 mile something trip to my girlfriends. Well, I'm doing 65MPH like he told me, and this thing is buring oil like crazy out the back. I didn't think anything of it, since he'd told me it did that and the oil pressure guage was sitting normal. Well, the whole way down I never stopped, just straight 65MPH on the highway the whole time. As soon as I got off the exit ramp, I noticed the van was running sort of rough, then I noticed the oil pressure guage was sort of starting to jump around. I had to stop at a light, then the Check Oil light comes on and the pressure guage is going from nothing to normal. I pulled over as soon as I could and let the van sit for a good 30 minutes. I checked the dipstick and it was bone dry. I put in the 2 quarts of Castrol that I'd brought with me (just in case) and waiting about 15 minutes before checking again: still bone dry. Having no more oil, and nothing being open around, I fire the van up and drive to the first service station. I buy 2 more quarts of oil and put them in. Now the oil is about a 1/3 of the way above the Add 1 Quart mark. So, before I got off the highway (when it was running just fine), the van probably had a quart or so of oil in it, plus whatever was left in the filter. Turns out that the gasket on the filter completely busted, and let all the oil drain out over the drive. The whole underside of the van was completely coated. I stopped at a quick change, had them put on a new filter, top up the oil, and everything was good. No one really uses the van anymore, but after sitting for a few months, it'll fire right up, no oil pressure problems or related sounds at all. Just goes to show that we probably worry way too much about oil and filters. [Smile] Chuck
 

MolaKule

Staff member
Messages
21,951
Location
Iowegia - USA
I would say for a 4 cyl. to a small 6, about 24 oz. to 1 1/2 quarts, depending on speed (rpm). At idle, about 24 oz. is circulating at any one time.
 
Messages
824
Location
San Jose area, CA
Well for sure at least the amount of oil in the bottom of the oil pan needed as a minimum to cover the intake tooil pump suction orifice. As you know if the oil pump sucks air too often it is neither good for the pump nor good for the engine.
 
Messages
8,711
Location
Nothern USA
quote:
Originally posted by MolaKule: I would say for a 4 cyl. to a small 6, about 24 oz. to 1 1/2 quarts, depending on speed (rpm). At idle, about 24 oz. is circulating at any one time.
Sounds like a good answer. Mind saying what you base it on? I think ruking77 makes a good point on covering the oil pickup.
 

MolaKule

Staff member
Messages
21,951
Location
Iowegia - USA
I once had the oil pan off of my old S-10 and ran a substitute sump tube to the oil pump from the wash tub (new sump). Measured height of oil on stick with engine not running verses engine running. Difference is volume of oil in circulation. The engine block shape was such that oil sling was minimal. At 800 rpm, oil in circulation was approx. 24 ozs or 3/4 Liter. V = pi*R^2*h.
 
Messages
1,397
Location
Katy, Texas
quote:
Originally posted by chucky2: I once borrowed my fathers '92 Ford Aerostar with the 4.0L V-6 to move down to college. This thing leaks some oil and burns a little also, it also has like 15X,XXX miles on it at the time. Anyways, I change the oil the day I leave(just dino Castrol, 10W-40 I think and a Fram filter), and then proceed to head down the highway for the 280 mile something trip to my girlfriends. Well, I'm doing 65MPH like he told me, and this thing is buring oil like crazy out the back. I didn't think anything of it, since he'd told me it did that and the oil pressure guage was sitting normal. Well, the whole way down I never stopped, just straight 65MPH on the highway the whole time. As soon as I got off the exit ramp, I noticed the van was running sort of rough, then I noticed the oil pressure guage was sort of starting to jump around. I had to stop at a light, then the Check Oil light comes on and the pressure guage is going from nothing to normal. I pulled over as soon as I could and let the van sit for a good 30 minutes. I checked the dipstick and it was bone dry. I put in the 2 quarts of Castrol that I'd brought with me (just in case) and waiting about 15 minutes before checking again: still bone dry. Having no more oil, and nothing being open around, I fire the van up and drive to the first service station. I buy 2 more quarts of oil and put them in. Now the oil is about a 1/3 of the way above the Add 1 Quart mark. So, before I got off the highway (when it was running just fine), the van probably had a quart or so of oil in it, plus whatever was left in the filter. Turns out that the gasket on the filter completely busted, and let all the oil drain out over the drive. The whole underside of the van was completely coated. I stopped at a quick change, had them put on a new filter, top up the oil, and everything was good. No one really uses the van anymore, but after sitting for a few months, it'll fire right up, no oil pressure problems or related sounds at all. Just goes to show that we probably worry way too much about oil and filters. [Smile] Chuck
We had a 1989 Ford Aerostar SWB with the 3.0L V6. It burned less than a quart over 3000 miles. This thing was so old that the shifter on the floor. It went to Mexico 13 times, New Orleans, California 3 times and was my dad's daily driver. It had 201,000 miles when we sold it and it was still running great. It ran on Frams..... so i guess we do worry too much about oil and filters.
 
Messages
9,448
Location
USA
Remember that that same engine at redline will barley keep the oil pickup covered. One of the reasons some companys are useing lower oil pressures is to make sure the pickup screen stays covered at high RPM's. It used to be odd to see an OEM car turn 6000 RPM's but now their are many that can turn 8000 or more RPM's some as high as 10,000 RPM's right off the show room floor! You could imagine that if you started with 35 psi at idle and then gained 10 psi per 1000 RPM's up to say 150psi bypass you would have a hard time keeping the pickup covered with a small oil pan. So one solution is to reduce oil pressure and the other is to increase the size of the pan.
 
Messages
1,533
Location
Ephraim
quote:
Originally posted by MolaKule: I would say for a 4 cyl. to a small 6, about 24 oz. to 1 1/2 quarts, depending on speed (rpm). At idle, about 24 oz. is circulating at any one time.
I would say you may be closer to the truth on one aspect, what is moving around the engine. But I think there would be a little more because there's still about 40-42 ounces in my engine after the oil has been drained. So perhaps someplace between 40-60 ounces or 1/3-1/2 gal. (and yes I know, youre in that range) but I still think a little more.
 
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