I have been using Mobil 1 in my wife's G35 Sedan since after 500 miles. Bought it brand new. I keep checking the oil and it doesn't use a drop of oil. I change the oil every 6000 miles.

 

"Under no circumstances should you burn nearly 2 qts of oil in 1800miles, unless you are beating the living crap out of your engine"

No I'm not beating the crap out of the engine. In fact I baby the car more now than ever.

I'll keep an eye on the levels for another 1k miles and see what happens. Hopefully a NNA tech will call give me soon and give me their take on the situation. I'll keep you guys posted too.

 

I have beaten the crap out of my car and have never had any problems...

 

So what type of oil are you using and how much are you actually burning?

What kind of driving are you doing? A new short block means zero break-in (unlike the car you got new, it's engine had ran a bit). I'm guessing the engine will burn oil as long as you don't load the engine (accelerate WOT from 30mph in sixth gear) to set the rings.

Engine braking, high rpm rev matching will burn oil.

Mobil 1 tends to "evaporate", I burn one quart every oil change on my car. No stress.

 

Uhm!!! No!!!

 

Sorry, I don't remember seeing you at any of my oil changes on my cars. But maybe you know more than me on my car's oil consumption and driving habits?

 

that is exactly what I was burning... been burning 1qt every oil change from first mile to 15K miles(constant)... then I switched to 300v and hardly burn anything.

I don't exactly drive like a ***, I also have a 2-3 oil analysis on the oil and engine has virtually, NO wear... so, uhm, yes!!!

 

Think whatever you want but I have a G35 and a 350Z. None of them use 1 quart of oil every oil change. I drive the **** out of them both and the G gets oil changes every 6K miles.

Hell, my 2-cycle RX-7's didn't even burn a quart of oil. (between oil changes)

 

Really? I do rev-match quite a bit. Why would that burn oil?

 

First off, burning some oil is normal for an engine. We can't escape it. Burning too much is something else. More than 1 quart after the break-in period would be cause for concern.

I was ready to accept your comment 350xfire that your cars don't burn oil (much). But you just lost some credibility on your comment of a rotary engine not burning oil... maybe you got the one magical RX-7 that didn't run on oil ?

Anyways, back to the rev-match thing.

The piston rings are not super tight in the cylinder. The spring loading alone is not enough to seal perfectly. A good thing because we'd see a lot of wear if they did. Instead, they rely on the cylinder pressure during the combustion phase to push down and out on the rings. Some pressure gets between the piston and the ring to push them on the cylinder surface and scrappe the excess oil.

So, when blipping for rev matching or using engine braking, there is very little cylinder pressure. As soon as you lift your foot from the gas pedal, the ecu cuts fuel to the cylinder. Running empty, there is no (relatively speaking) cylinder pressure to help the rings seal correctly and some oil makes its way into the combustion chamber. That oil is burned as soon as you get back on power.

Repeat that over many cycles and voila, some oil is missing when you do your oil change.

 

I didn't say my RX-7's did not burn oil, I said not as much as 1 quart per oil change. It is well known that, because the rotaries are 2 cycle, they WILL burn oil. This is something ALL rotary owners have to live with.

Still, the main point I am trying to make is that on my G35 (sedan auto) I can run 6000 miles and I don't lose a drop of oil. On the 350Z, I have not lost any in 800 miles. I don't drive the Z that often, just my weekend car but I do beat on it a bit.

Accept my comments or not, I still don't think a piston engine should lose that much oil (1 quart?) between 3-4000 miles. Enough said, I'm out of this one.

 

There. Auto trannies don't see much engine braking, if at all. It's not like you could control them 100%

And 800 miles is not enough to see any difference on the dipstick. Just have a look at how much oil will comme out of the car when you do your next oil change. Remember that some will be in the oil filter (~3/8 of a quart).

Ah, and pages 8-10 of the owner manual says:

 

Ok, this is interesting. I've repeatedly asked the master tech at the dealer if I could be doing something wrong. Neither he nor anyone else at the dealership has mentioned any of this to me.

If what you say is true, it may be possible that this issue started soon after I learned to heel-toe. I heel-toe and blip regularly for smoother downshifts and occasionally for subtle engine braking. I'll change my driving habits for 1k miles or so and see if there's a noticeable difference in the oil levels.

NNA could have saved us both a lot of time and money if they would have looked into this and stated what you just said. I probably would not have believed them at first, but if I don't burn as much oil as a result of changing my driving habits, then it's safe to say that we could have resolved this months ago. I'm going to start another thread and see if other "oil burners" have the same driving habits as me. Thanks for your input Kolia.

 

I also heel-toe and rev-match, and have oil consumption of 1 quart every 2k miles.

 

The important is to realize that it is POSSIBLE to burn off some oil, especially if you driver very hard (manual / track). It also appears that some oil are more prone to "burning off" than others. I would worry if given a consistent driving style oil consumption increases oil change after oil change.

If you want to be worry free without going to dealer, have a compression test done, or even a leakdown test and get your oil analyzed every 1-2 oil changes. (costs 30$ and gives you very good idea of wear engine is going through).

 

By tight, I am refering to the end gaps being much smaller on OEM cast pistons, vs. a forged piston. Forged pistons for FI applications run larger ring end gaps, and also much larger piston to wall clearances. Factory is sub .001 and most forged pistons are in the .002-.005 piston to wall clearance. Forged motors tend to burn a tad more oil, than a factory spec OEM engine. Even my forged engines are burning no more than 1/2 to 3/4 quart per oil change.

Generally speaking, if you are burning more than 1 qt of oil every oil change, I'd be examining the health of the motor.

Do the compression/leakdown that I mentioned....it will tell you at LOT of things about your engine.

 

you also use much thicker oils and different compression ratios, different rings, etc... try using 5w30 in your forged engines and we will see how much you burn.. A too tight piston/wall tollerance could lead to more oil actually being burned.

here is a nice paper

http://www.hastingsmfg.com/Service%2...il_control.htm

Kolia is also a dedicated track junkie, his engine is a tad more "exercised" than average.

 

Piston to wall clearance is determined by the piston manufacturer, based on the material and design of the piston forging, and the intended use for the engine.

I have been very pleased with my bearing conditions, using the viscosity I am currently using, so I have no plans to change. 1/2 per oil change is fine by my standards.

FYI: Porsche's and other exotic cars, already run forged pistons/rods, so it would not surprise me if they burn a tad more oil.

 

Sharif is correct! My dad has a Porsche Boxster and hardly ever drives it hard. He maybe has only 1,800 miles on it and last summer he had to add 1 qt of Mobil 1.

So is it safe to assue that Mobil 1 oil sucks in that it will evaporate overtime?

Since I have started my oil consumptiontest I have driven 250 miles and not a single drop gone on the dealership oil. Could my problem been with the Mobil 1 oil?? Yet others hav had no problems at all with Mobil 1...

confused...

 

A friend of mine just had his tranny replaced for the 2nd time. The dealer told him that if they had to replace it again, the car would be considered a lemon!