Minor Oil Leak?

G

giraffophobic

Member
 Virginia, United States
Currently trying to determine if I have a minor oil leak. I did an oil change about a month and a half ago right after purchasing the car, and in that time have travelled about 1700 miles. Since then I've lost a half a quart of oil, according to the oil level sensor on the dash. I'm aware that on my Z (2006 3.0si), the valve cover gaskets tend to go at about the odometer reading I'm at (~96k miles), however neither my mechanic nor I could locate any leaks or puddles/dripping, there was no burning oil smell or blue exhaust, and zero overheating. Unsure if the previous owner had any oil-relevant gaskets replaced. Currently runs fine.

I'd imagine that the aging gaskets probably contribute to a slight amount of oil consumption, but I'm just curious if losing .5 quarts over 1700 miles (.47 liters / 2736 km) is reasonable, or if I have reason to be concerned. Initially posted this question in r/BMWZ4.

Let me know if I posted this to the wrong place, I'm new here 8)
 
Some cars can be very sensitive to the type of oil used - some can increase consumption whilst others reduce it. Half a litre in 1700 miles isn't out of the ordinary, Alfa for example won't look at it unless its greater than 1 litre per 1000 miles! But if you poured half a litre of oil on your drive you'd soon spot it so it doesn't sound like a leak to me.
 
If you and your mechanic an’t find any leaks then your car is probably burning oil.

While half a quart every 1,700 miles is not excessive, it may be worth getting a compression test, or better yet a leak down test at your next service to establish the health of your head gasket, especially as your car has nearly done 100,000 miles.
 
Rockhopper said:
Half a litre in 1700 miles isn't out of the ordinary, Alfa for example won't look at it unless its greater than 1 litre per 1000 miles!
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I believe BMW set a standard at 750 miles (https://www.justanswer.com/bmw/1devp-2004-bmw-z4-seems-consuming-high-amount.html), but I was certainly surprised to see that much oil lost.

R60BBA said:
While half a quart every 1,700 miles is not excessive, it may be worth getting a compression test, or better yet a leak down test at your next service to establish the health of your head gasket, especially as your car has nearly done 100,000 miles.
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Hoping to make it into the shop this Friday to get a leak down test, I'm hoping there isn't any sort of head gasket issue. Would coolant mixing with the oil be indicative of a head gasket leak? My oil quality seems fine by my quick inspection of the color and cleanliness. I'm hoping to rule out the possibility of a head gasket leak. There does not seem to be an excess of exhaust, nor is it abnormally colored.

Thank you both :thumbsup:
 
Sounds like I'm treating you as a fool, but not intending to................

Are you sure it was filled right up when you did the oil change? Is possible that once it got up and running, then the oil settled and was a little below max.
I'm trying to be optimistic here and hope it was something simple and you've not lost any oil at all. :)
 
enuff_zed said:
Are you sure it was filled right up when you did the oil change? Is possible that once it got up and running, then the oil settled and was a little below max.
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No worries! Oil was filled almost to max capacity according to the sensor, but in the 1.5 month period since then the sensor has been reading progressively lower oil levels
 
Welcome to the forum. :thumbsup:

My last 3.0Si used about a litre (1.05 Quarts) in 4,000 miles between 82 and 86K miles, so the oil use you have experienced doesn't sound excessive.

I've now got a 330i with the same engine and that is using a fair bit more, but that's because it's leaking from the oil filter housing - but if yours is leaking there it should be pretty obvious as I get a little puddle on the top of the engine (and under the car)! I plan to get it sorted at the next oil service.

By the way we do like to see photos of new members' cars on here. :lol:
 
My 3.0Si uses way less than that, I never have to top it up between oil changes so less than 100ml / 1000miles.

It’s probably CCV related (crankcase ventilation). The black top N52K had a revised CCV system fitted so not sure which engine you have?

In any case, first thing to do is remove the top DISA valve (the one that’s easy to get to) and see how much oil you have in the intake. Lots of oil = bad CCV.

Also, check amount of vacuum you have on the oil filler cap with the engine running compared to my YouTube video here... https://youtu.be/VhcqVSkhIeA
 
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