Oil consumption Non Linear?

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I have noticed something I find baffling....on my 96 Q45 oil consumption is not linear at all- for instance on a fresh fill of Redline 0w-30 oil is 11 ounces low after 2300 miles of use{which I measure and refill} then the next 1000 miles of driving consume 15 ounces....driving pattern is identical which consists of a 120 mile daily roundtrip all highway at speeds of 80-95mph. This pattern has been similar for almost every oil change interval,any ideas????
 
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I think it's a sign of fuel dilution and poor piston/ring seal. Some engines though, consume oil by design. The Honda won't consume much oil up to 3,000 miles, but from 3-5k, it uses 1/2qt or more depending on how I drive.
 
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While that must be frustrating, it isn't a huge amount of consumption. Might be worth trying a cleanse with your favorite product (MMO/ARX/whatever) and see if that helps. Best,
 
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I was wondering if whether or not you added the 11oz make up oil before the next 1000 miles of monitoring the oil usage?
 

qship1996

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I add the 11 oz of oil at 2300 miles to bring level on dipstick back up to the full level. Oil analysis always come back great, no fuel found and all other numbers great.{I have used redline only in this car for the last 150,000+ miles} total miles on car are 240,000 and it still runs like new.
 
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Well I guess that rules out a decrease in oil fill as a factor. You are seeing almost the eq. of 3x rate of consumption after the first 2300 miles looks like.
 

qship1996

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Predictable....it always takes about 2300 miles from a fresh oil change for the level on dipstick to drop about 1/2 way{ 11 ounces} then I refill and from then on it consumes oil at a quicker rate. I end up using 1.5 quarts makeup oil over a 6000-6500 oci.
 
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Tried using thicker oil to slow down the oil burning? Doesn't the 0w shear much? Maybe using as your make up oil: 10w40 or 5w40 in the winter, and 15w40 in the summer. IMO cars with quite a bit of milage and wear like their oil a little thicker than in their youth. As to theories, I like the theory proposed above on fuel accumulation in the oil during the OCI. Also, I've noticed that it seems (not sure, but it sure seemed like it), that if the engine is low on oil, it burns the oil faster. I was thinking, maybe... with 3 liters of oil absorbing the engine's heat and friction, each molecule of oil would be working harder(absorbing more heat) than if the oil was topped a bit above full and running with 5 quarts of oil. Also besides thicker oil and not running the oil low, maybe a moly treatment would do good here.
 
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qship1996

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I used redline 10w-40 this past summer,same exact consumption!!1 Maybe the high speed commute has something to do with usage?
 

gathermewool

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Originally Posted By: qship1996
I used redline 10w-40 this past summer,same exact consumption!!1 Maybe the high speed commute has something to do with usage?
Bingo! haha
 
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Hmmm, well, it's not the worst oil consumption but it isn't great. If it were me I sure would be using cheap to medium priced thick make up dino oil. On an OCI of like 5K, that's like a little over 2 quarts of make up oil; I guess not a big added expense, maybe $7 in extra oil, or less if you buy by the gallon at a sale.
 
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Be careful with relaying theories around here, some one might require you to provide laboratory proof to back them up or they are wrong grin. I guess depending on the oil shearing and thinning of the oil and it getting into cylinders and the PCV could be a possibility. It's just interesting that it happens like clockwork for the OP.
 
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Originally Posted By: qship1996
Predictable....it always takes about 2300 miles from a fresh oil change for the level on dipstick to drop about 1/2 way{ 11 ounces} then I refill and from then on it consumes oil at a quicker rate. I end up using 1.5 quarts makeup oil over a 6000-6500 oci.
Just wait to add a full quart and see if it's at the mileage you expect. Normally non-linear consumption points to oil fatigue of some sort. Straight line consumption points to design/mechanical origins.
 
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what other oils have you tried other than Red Line? have you tried any non-Group V synthetics? how about oils with high Group IV or low Group IV? how about dino oils? and HDEOs like Delvac or Rotella?
 
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Originally Posted By: mechanicx
Be careful with relaying theories around here, some one might require you to provide laboratory proof to back them up or they are wrong grin.
Yes you'll need pictures, fleet tests, before and after compression readings, to back your observations up. banana A buddy of mine bought a beater car which used oil similar to what the OP is mentioning here. A Bitog buddy told me about Schaeffers #132, and sent me some, months ago. I passed a bottle along to my friend and he found that adding the Schaeffers #132 for the first top up, held him till he changes the oil without having to add any more make up oil. He hasn't added it from the get go just yet, but it is helping him. Might be worth a try.
 
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Originally Posted By: qship1996
I have noticed something I find baffling....on my 96 Q45 oil consumption is not linear at all- for instance on a fresh fill of Redline 0w-30 oil is 11 ounces low after 2300 miles of use{which I measure and refill} then the next 1000 miles of driving consume 15 ounces....driving pattern is identical which consists of a 120 mile daily roundtrip all highway at speeds of 80-95mph. This pattern has been similar for almost every oil change interval,any ideas????
try their 10w-30 and report back
 
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had a similar situation on the 92 Camry 4cyl. 170K miles 5K oil changes with whatever 5-30 dino first 2K miles = full on dipstick. By the time it got to the 5K change, it had consumed a full quart. I usually did not add any between 2 and 5 K because it was not at the add line till 5K. Only motor I've ever had with this pattern of consumption Steve
 
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my 2005 cadillac cts is doing the same thing. I'm running an oil consumption test of my own to see if its linear or not on my car and here's the result with Mobil 1. New oil change July 9th at 179376 km. August 31st, 5218kms later: 0.7 qt added September 29th, 4455kms later: 1 qt added October 29th, 4295kms later, 0.6 qt added December 7th, 2871kms later, 0,7 qt added I change the oil per the OLM and I'm at 7% engine oil life remaining as per today so I'll do the oil change this weekend. I think its due to oil fatigue but its very non-consistent and I'm telling myself that it could only be due to oil fatigue or too much idling when working, I don't know. I do know that Cadillac are oil users... If you want, I can post the exact same thing for PP 5w30 but it was worst. The car used 3 qt after 12000kms. I'm at 3 qt right now with M1 5w30 but for 17678kms.
 
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