Oil Consumption with Different oils?

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thescreensavers

thescreensavers

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What Causes oil consumption of the same Viscosity Grade (5W-30)?

I have used Brands "X" and "A", but a certain "Premium" oil from Brand "A" causes me to loose a little over half a quart in 2k miles. Where as Brand "X" and another Synthetic from the same Company "A" consumes a normal 1/4-1/2 quart in 5k miles.


So my question is why does this happen, I am not saying the oil is bad or anything, I just want to figure out what and why this happens were one oil to burns more than the other?
 
I realized huge difference between semi-synthetic and fully synthetic oils. Difference for me: better heat stability of full synthetic one.
 
I'll do you one better: until my current oil, my lowest rate of oil consumption was with a 5w-30; my highest was with a 5w-40. That's the opposite of what conventional intuition suggests.
wink.gif


Here's what I understand about this topic.

There are a few possible causes for oil consumption.

1: Leaks. Oils that cause seals to swell, or retain more of their viscosity at high temperatures, could do better here.

2: Loose piston rings. Oils that seal the combustion chamber well, resist fuel dilution, resist burn-off, and/or retain more of their viscosity at high temperatures could do better here.

3. Oil vaporizing in the crankcase and then being breathed into the intake through the PCV system. Oils with lower volatility could help with this.

4. Oil foaming in the crankcase due to being whipped up by the crankshaft, causing the oil level to rise. (this will show up with long, continuous highway trips). Oils with better foaming resistance could help here.
 
Originally Posted By: d00df00d
I'll do you one better: until my current oil, my lowest rate of oil consumption was with a 5w-30; my highest was with a 5w-40. That's the opposite of what conventional intuition suggests.
wink.gif


Here's what I understand about this topic.

There are a few possible causes for oil consumption.

1: Leaks. Oils that cause seals to swell, or retain more of their viscosity at high temperatures, could do better here.

2: Loose piston rings. Oils that seal the combustion chamber well, resist fuel dilution, resist burn-off, and/or retain more of their viscosity at high temperatures could do better here.

3. Oil vaporizing in the crankcase and then being breathed into the intake through the PCV system. Oils with lower volatility could help with this.

4. Oil foaming in the crankcase due to being whipped up by the crankshaft, causing the oil level to rise. (this will show up with long, continuous highway trips). Oils with better foaming resistance could help here.



While everything you point out is true, additive packs can have BIG differences in oil uasage, it also has to do with the metal casting of the engine, additives can react differently with the type of casting methods , and the metals themselves .
 
A few years back I did a run with QS conventional 5W30 in my daughter's 1999 Accord and it consumed it at a surprising rate. Decided I better try something else and used Mobil 5000 5W30 with minimal consumption.

Tried the Mobil 5000 10W30 in my inboard boat since it worked well in the Accord, and it seemed low visc when I drained it. Went to Delo 15W40 and it sounded quieter.

Consumption is one of the attributes we use to find an oil that an engine "likes."
 
Originally Posted By: skellyman
While everything you point out is true, additive packs can have BIG differences in oil uasage, it also has to do with the metal casting of the engine, additives can react differently with the type of casting methods , and the metals themselves .

Of course. Additive packs affect most of the factors I listed.
wink.gif
 
Originally Posted By: LeakySeals
Is some of it NOACK?


In my opinion, a lot of it is NOACK.
Seal conditioning agents of HM oils can help in some cases.
d00df00d had good comments on the various characteristics.
 
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Have not been able to pin differences due to NOACK - the engine block is relatively "cold" and will cause a condensate return to sump. Plus noack (astmd5400) is run at high oil temps (300degF)which may be only seen in severe towing or racing in loaclised engine hot spots.
 
With my 1996 Contour Zetec 4 if I start using Mobil 1 after using another oil I'll "use" maybe less a 1/2 quart in 4000 miles. After that I don't use any on that OCI or any subsequent oil changes with Mobil 1. My wife's 2005 Explorer with the 4.6 uses no oil with Mobil 1 at all.

Whimsey
 
Quote:
Base oil differences additive packages...


While some additive packages can have an effect, such as the amount and type of seal swell and detergency it is mostly due to the mix of base oil viscosities. Base oils are a mix of two or more viscosities. If one of the base oils is not a much higher viscosity than the viscosity weight, then it will be more volatile (higher burn off) and will not seal the rings or valve stem seals.

And yes, M1 HM is one of the better OTS oils if you have oil consumption issues.
 
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Reminds me of the craziness helping my gf research her 1997 Saturn SL Oil consumption......I looked high and low.....some posts recommended 5W-20, with no "oil consumption" problems......others mentioned going to a 5W or 15W-40 "diesel grade" oil.....i.e.: thicker oil "should" leak/burn less.....realistically at least :P


But then I recall a post where a dude was using 5W-20 in his Saturn, with NO problems whatsoever as far as oil loss/consumption :P Go figure, right....? Seems similar to this instance with the Accord mentioned.....higher consumption with the higher weight oil, et. all....
 
Originally Posted By: ahoier
Reminds me of the craziness helping my gf research her 1997 Saturn SL Oil consumption......I looked high and low.....some posts recommended 5W-20, with no "oil consumption" problems......others mentioned going to a 5W or 15W-40 "diesel grade" oil.....i.e.: thicker oil "should" leak/burn less.....realistically at least :P


But then I recall a post where a dude was using 5W-20 in his Saturn, with NO problems whatsoever as far as oil loss/consumption :P Go figure, right....? Seems similar to this instance with the Accord mentioned.....higher consumption with the higher weight oil, et. all....


Those SL Saturns pre '02 had ring issues that caused all that oil consumption. I found consumption to be roughly equal to anything else I tried (up to 5w50, which caused some bad noises, and down to 5w30) with Delvac 15w40 and stuck with it because it was cheap and came in nice gallon containers. 3 Auto-RX treatments cut my consumption in half on that car though, down from 1qt/1k to 1qt/2k.

--Matt
 
my 2 cents is that a spec is not a pure discrete hard and fast specification but represents a range.

So one oil might be on the high side of the range and the other the low.

FWIW, mobil1 full synthetic 5w-30 consumes in some of my cars versus PP 5w-30
 
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