epsalant Posted April 8, 2018 Report Share Posted April 8, 2018 When I get my oil changed in my 1989 M20J, I have the mechanic put in 7 qt oil. (One for the filter, the dipstick reads "6") For the next ten or so hours, my engine seems to use no oil. Then it starts to require (in order to keep the level at 6 qts, where I like it) about 1/2 qt every 2.5-3 hr. My mechanic said it's not unusual for engines to use less oil right after an oil change. Why is this ? Why should the engine burn less oil right after an oil change ? Quote Link to comment Share on other sites More sharing options...
epsalant Posted April 9, 2018 Author Report Share Posted April 9, 2018 I believe him (and You !), wondering about the "Why ?". Quote Link to comment Share on other sites More sharing options...
Marauder Posted April 9, 2018 Report Share Posted April 9, 2018 I believe him (and You !), wondering about the "Why ?". I noticed the same thing for the 27 years I have owned my Mooney. I personally think the viscosity breaks down a little and it either gets blown out or burned easier. I do notice more oil coming out of the breather the longer the oil has been in service. Sent from my iPhone using Tapatalk Pro 2 Quote Link to comment Share on other sites More sharing options...
Bartman Posted April 9, 2018 Report Share Posted April 9, 2018 Same Quote Link to comment Share on other sites More sharing options...
Oscar Avalle Posted April 9, 2018 Report Share Posted April 9, 2018 same Quote Link to comment Share on other sites More sharing options...
carusoam Posted April 9, 2018 Report Share Posted April 9, 2018 Can we ask Ed kohlen (sp?) our technical oil guy... We have a few MS guys with technical backgrounds regarding engine oil analysis, both aviation and non-aviation... Our oil sees some really hot spots for brief periods of time... around exhaust valve guides... molecular breakdown over time is expected... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
mike_elliott Posted April 9, 2018 Report Share Posted April 9, 2018 Im not sure Ed Kollen monitors this board. He took a bit of abuse here a while back and was run off. 1 Quote Link to comment Share on other sites More sharing options...
AH-1 Cobra Pilot Posted April 9, 2018 Report Share Posted April 9, 2018 Is the dip stick calibrated via length, not true volume? It could be the shape of the oil reservoir. If it is broad and flat near the 6 quart mark and narrower at a lower capacity, it will only seem as if the oil disappears at a faster rate the lower the level is. This could also be the case if there is more machinery in the oil at the lower levels. Quote Link to comment Share on other sites More sharing options...
AlexLev Posted April 9, 2018 Report Share Posted April 9, 2018 The way my flight instructor explained this in the past is some of the protective elements/additives in the oil start to breakdown after 10-15hours. Not a super technical explanation, but hopefully someone with more knowledge can provide more insight. Quote Link to comment Share on other sites More sharing options...
LANCECASPER Posted April 9, 2018 Report Share Posted April 9, 2018 15 hours ago, Marauder said: I noticed the same thing for the 27 years I have owned my Mooney. I personally think the viscosity breaks down a little and it either gets blown out or burned easier. I do notice more oil coming out of the breather the longer the oil has been in service. I've noticed the same thing here. Heat is what breaks the oil down and that's why the oil change intervals on turbo charged engines are shorter than on normally aspirated engines. 1 Quote Link to comment Share on other sites More sharing options...
Bravoman Posted April 9, 2018 Report Share Posted April 9, 2018 4 minutes ago, LANCECASPER said: I've noticed the same thing here. Heat is what breaks the oil down and that's why the oil change intervals on turbo charged engines are shorter than on normally aspirated engines. Along these lines I am delighted to say that my factory reman which now has about 230 hours on it uses a quart every 14 or 15 hours. I couldn’t be happier with the way it is running. Quote Link to comment Share on other sites More sharing options...
DXB Posted April 9, 2018 Report Share Posted April 9, 2018 I've heard about it on here many times, but I have never noticed this phenomenon despite tracking my oil consumption religiously. I really wonder if it happens in all engines. Back before my cylinder work, it would blow off 1 qt/3-5 hrs no matter what. Now it loses only 1qt/ 15 hrs no matter what. I just went 40 hours between oil changes and only needed to add 2 qts in the interim. I'm not really sure whether that's a good thing or not, but it sure is a dramatic change. Quote Link to comment Share on other sites More sharing options...
jackn Posted April 9, 2018 Report Share Posted April 9, 2018 I also have heard that this is a real phenomenon. What is happening is that the long molecular strands, through a process of heat & mechanical action, break these strands up. Synthetic oils are long thin strands, whereas mineral oils are branchy. Therefore you should see more oil usage with the synthetics from the get-go. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted April 9, 2018 Report Share Posted April 9, 2018 I just thought it was the viscosity is lowered by various byproducts (water, avgas, etc) that results in more oil being blown out? 1 Quote Link to comment Share on other sites More sharing options...
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