Most of us know that some of these engines burn some oil and others not so much. This is my experience so far.

Our Infiniti G35 Coupe just got done a 6k mile run of Mobil 1 0W-40 and I'm pleased to report that oil consumption was considerably lower with this oil than Gold German Castrol and Syntec 10W-30.

The car was bought used with 17K miles on it. I used GC for the first 3 OCI's then Syntec 10W-30, then M1 0W-40. Engine now has 42.5K miles on it. The consumption with GC on all 3 OCI's was by far the most and was not improving despite being used for a total of over 15K miles. Oddly consumption lessened on Syntec 10W-30. It lessened even more with Mobil 1 0W-40. Today I put in a mix of M1 0W-40 and 10W-30 High Mileage. Autozone didn't have enough of the 10W-30 HM so I settled for a mix.

Man this engine turns the oils dark...scary dark.

I have a 2003 G35 sedan that doesn't consume any oil, but it sure gets dark in color quickly. A recent UOA by Terry Dyson showed elevated fuel and silicon that even GC couldn't combat for elevated Pb. A concurrent UOA with Blackstone did not pick up the fuel or flashpoint problem. The TBN was down to 2.1 after only 4113 miles (65K total). To make a long story short, I replaced the air filter and cleaned out the intake box real good, changed the plugs (one came out soaked with oil so I had to replace the valve cover just to replace the defective hardened ring seal), and replaced the PCV. The platinum NGK spark plugs were down to nubs after only 65K miles.
I'm not sure who you are using for analysis, but Terry can help you find out what's wrong with your car. There will be no guessing (which is what I have gotten from other labs).

I have a 2005 Altima 3.5 and the only oil that I tryed that does not get black quickly is Rotella 10w30.

Thank you for your post. BTW, there's nothing wrong with the engine as far as I know. Yeah I replaced the air filter too. It gets filthy so fast. Based on your spark plugs, I'm going to check mine now. I'm also planning on checking the PCV valve to make sure it's clean. Where is the PCV valve on these engines and it is an easy to remove? Thanks.

That's cool, steveh. I look for that oil at the stores but never see it.

If the VQ35 is similar to my VQ30 ('97 Maxima), the PCV is underneath the throttle body.

Dave

JAG,

Don't let "oil that gets dirty quickly" bother you. The M-1 0w40 on my former Saab 9-3 was noticeably darker within 500 miles of an oil change.

I was not impressed with green GC in my '01 I30 (VQ30DE) after only 5k miles. The TBN was lower than I'd have liked and it was not all fuel dilution, either. That's with three 5k runs with the green and an analysis each time.

I pulled my 105k mile NGKs after only 56k miles (and replaced them). They looked like they had another 35k miles on them. The PCV valve is a must change on this engine about every two years or 25k miles.

No oil consumption issues with mine. Mine just eats O2 sensors and my forward cat.

I'm running Maxlife full syn (API-SL) right now. BIOSYN 10w30 SHP to follow after 5k. Stay tuned and good luck.

The PCV is the easiest thing to change on the car (unlike the air filter). As you face the engine, you will see about a 3/4" black hose attached to it on top of your valve cover (on your left). It's only about 4-5" back from the front of your valve cover. Just loosen the hose clamp and pill the hose off of the PCV, unscrew it, replace it, and then put the hose back on. I bought a replacement at Infinity. And as usual, a $3 part cost $20! You might be able to do better at an auto parts store.

Thank you all! I'm excited to change the easy-to-change PCV valve. My other car, VW 1.8T, requires a PHD to change the PCV valve.

Try cleaning the PCV valve with brake cleaner or a similar solvent before you spring for a new one.

Do you know how many oil changes your G35 had before you got it at 17k?

Yeah I'll try brake cleaner on the PCV valve first.
I don't know the oil change history from before we bought it but the engine was and still is clean inside.

Jag,

You look like you're on the right track. Go to some owner forums and study experiences. If PCV clogging is excessive look for low volitility (Noack%)

Look at the weights; _W30 compared to M1 0W40. W40 should consume less generally, although you are comparing a thick W30 (GC) to a thin W40 as I understand.

M1 0W40 European - Probably the best spec'd oil for Euro mfg's. (Just try meeting these spec's with pure Grp III.)Is W40 ok in your app ? You could move to M1 10W30 High Mileage (ACEA A3 rates), another lonely standout in M1 line.

Syntec 5W40 is another like M1 0W40 but the spec's are older from what I've seen. Syntec 10W30...not outstanding in this regard.

JAG,
350Z owner here with about 60 UOA's done on VQ35's from different 350Z's. Tracking mileage on the oil, qt's added, and driving conditions. The oils all show similiar behaviours between brands and weights, even though it's different climates and driving styles. I can say this:
Amsoil TSO 0W-30 looks great. Five different UOA's done, and all were within a few ppm and very low wear. Even up to 9k miles.
Amsoil ASL 5W-30 has decent wear numbers on four different engines, but the lead was higher than the TSO, especially after 6500 miles.
Schaeffer's 7000 5W-30 is the best peforming oil to date in terms of wear numbers. TBN not as good as the rest for long OCI's.
Mobil1 0W-40, about the best "off the shelf" oil tested so far. Waer numbers as low as TSO, except for Fe. Good TBN for extended drains, and seesm to be shear stable as a thick 30wt.
PP 10W-30 has shown great wear numbers as well, as low or better than the M1 0W-40 and TSO, but the TBN is always low and doesn't seem to be a good option for OCI's longer than 5k miles.
Royal Purple sucks. The 10W-30 is an average oil, and the 5W-30 is rediculous in wear numbers and shearing to a 20wt in two different engines.
The rest of the M1 weights are all average and don't appear to be worth the money. The M1 0W-40 is a consistantly better performer than the other M1 weights in the VQ35.
Motul is expensive and hyped, but the 300V series 5W-30 is an average performing oil at best in terms of wear with really high values for Fe. I don't know why the Z crowd loves it besides the fact that Motul is a GT500 350Z sponsor.
Shell T-Syn is in mine right now and another guy's Z, UOA's to come on both of our engines to compare to the others. The M1 0W-40 won't treat you wrong. The VQ seems to be brutal on oil. I wouldn't worry about the dark color, when you consider the amount of detergents XOM brags about in their M1 oils. Did you see the taxi cab test where the M1 cleaned the inside of some bowties in a Las Vegas taxi fleet?

And I don't know if the VQ30 would really be able to compare to the VQ35 in terms of oil UOA results. The crank and conrod journals are the same, and so is the cam on bucket design, but the bearings are different, and the VQ35 uses a hydraulic CVTC system on the intake side (and exhaust on the rev-ups). So, the oil demands are slightly different in my mind. But I'm a big believer in the notion that comparing UOA's from different engines are useless, but comparisons can be made and consistancies found in comparing UOA's of the same oil in the same engine used in different cars.
Will

Thanks for the posts guys. Yeah these VQ35 engines are hard on oils. They kill the TBN quickly. I'd say more but don't have the time right now!

Some excellent posts here.

I've done a couple oil changes on my gf's 2003 G35 coupe and I'll be sending away the oil from the first change soon, which was Mobil 10w-30 and ~12,000 kms or so. Right now it's in the auto-rx rinse phase with Rotella 10w-30 CJ-4 and than we'll probably go with that oil after and get a uoa to see how it performs.

On a side note, when I was dumping the oil from the "clean" phase, it was some of the most rancid smelling stuff I've ever encountered and DARK.