You nailed it... I'm in Arizona, cold starts are rare... This is 90% track car... Once oil is up to temperature, my understanding is that even 15w50 acts 'thin'... also despite the viscosity, it is rated at 0% shear loss... Finally, I'm relying in part on the recommendation of other racers in AZ

What oil are you using? (sorry if I missed it)

I am not from an oil research company :)

I started this as I noticed that my car consumed about half a qt of Nissan Ester oil (possibly up to a qt.) about 600 miles. I am wondering if it is the engine, the way I drive, the oil itself, or probably all of the above.

I'm still on the Nissan Ester oil, I may change to something else later once I hit 5000 miles. Not sure what oil that might be yet.

Travis is right on about oil viscosity. Here's a couple of typical viscosity numbers for you.

Sorry about the formatting, doesn't want to space correctly.
_________5W-30 ________ 15W-50
100F ____ 57 cSt ________ 143 cSt
220F ____ 10 cSt ________ 20 cSt

So the 15W-50 is nearly 3 times as thick at air temperatures, but twice only twice as thick at high temperatures. As the oil temperatures continue to climb towards 260 the viscosity is going to be close to 5W-30 at normal cruise around town temperatures.

Basically the oil is going to hold up better at the track but you might pay the price of increased start-up wear so it's not a good choice for a daily driver oil.

Yup...:iagree: Here's some info to back that up:

http://images50.fotki.com/v1512/phot...ture400-vi.gif

That's a nice chart. Just curious where you got that from and if the site had any further info.

+1 rep for data ! :) thanks modshack

How are you checking your engine oil level? Cold engine dipstick method or start up, bring the oil up to operating temp, turn engine off, wait 15-20 mins and then check it with the dipstick?

Can't recall where I got that as I was doing some general Viscosity/temp research and stumbled on it...

OEM oil 0-2,500 miles, no consumption
Castrol GTX 2,500-6,000 miles, no consumption
Castrol GTX 6,000- 8,900 miles, no consumption

Hey, I had data too ... his was just prettier :)

Sorry, didn't scroll up ! +1 for you too :)

Left the office for home (30 miles), parked the car in the garage, waited when the car was warm, then I checked.

I'll do your method....which is waiting for 20 minutes tomorrow.

If I continue to consume oil, I'll probably switch brand (Amsoil or Motul). If I continue to use oil, I may have the dealer perform a compression and leakdown.

I know that on Porsches, it is normal to use 1 qt every 1K miles (to my recollection). But on the Z, I do not know the norm. I will also check the manual to see if there is a norm.

Well, I think I am taking my car in. I have used 2.5 qts/2000 miles.

On my other car, it is normal to use up to 1 qt every 800 miles. On the Z, I called the dealer and they said they do not know the norm. The service department did say that over 2 qts is a lot more than what they wanted to hear.


Worst case scenario, If (and "if") they need to replace the engine (due to rings, or what-have-yah), what do you guys think? I just don't trust the dealer putting a new engine and some mechanic ends up doing short cuts (e.g., a washer, nut, bolt, or so being not re-installed). I guess getting a brand new replacement is out of the question? :)

Do you have any visible signs of leaks ? have you seriously checked over your car ? any deposits on your garage floor or parking spot ?

As for new engines, Coulter Nissan in Phoenix AZ is the first dealer in the US to replace an engine in this car. Call them and ask for Nick the service manager if you want to know about how that went. It was my car. As far as I'm concerned, good as new. In fact, I got 4 more hp on the dyno ! :)