I'm not sure what you're getting at. Like I said, I've always had the oil changed well before the 7500 mile interval as recommended in the manual and usually well within the 3500 mile interval since I make some short trips. The engine is not knocking (any more than the typical G35 spark knock) or making any strange noises. Engine temps are good. Performance is fine. So up until now there has been no reason to check the oil level more than every 3-4k miles.

I will now of course since a potential problem has been detected.

 

OP try thicker oil

 

the oil consumption issue seems to pop up at all mileages on these cars. i figure as long as its not a quart a month ill just add oil and keep drivin the G...until its time for a new car

 

I've been checking the oil frequently since going to the track. It has been about 1000 miles and 6 weeks and it looks to be about 1/2 quart low. It still measured full following the two days at the track.

Looks like I'm going to have to check the oil diligently every 1000 miles.

Performance is still good. No problems.

But, I have to admit, it is aggravating. I've have had 8 or 9 vehicles in my life and have driven all of them to high miles. None of them have ever had oil loss issues. Not even my 1976 Jeep Cherokee, which may be one of the worst vehicles ever made. Everything else malfunctioned but it did not use or leak oil.

 

Synthetic oil is designed as an extended mileage oil but you have to take into consideration alot of factors. Heat breaks down both regular and synthetic oil but synthetic takes longer. With turbo cars I will change synthetic oil at or before 3 thousand miles, if I have tracked or drag/street raced it alot it will be much sooner. NA cars don't cook the oil near as much but you also have to factor in the ambient temperatures and how hard you drive the car. On our G I will change around every 3-3.5 K because it uses about a quart in between oil changes and I don't like wasting too much new synthetic on topping off.

Other than heat you also accumulate hydrocarbons in the oil from unburnt fuel in the blow by gasses. This accumulation is the same for both synthetic and regular oil. For this reason I would never follow those high mileage change reccomendations.
If I lived in a cooler climate area and the G didn't use any oil I would probably change synthetic every 5K but Texas heat is a killer and my size 12 foot is made of lead.

 

5k miles later I have switched to a conventional motor oil. I am still.consuming 1qt per 500 miles, but at least I know its not the expensive kind lol.

Car still runs beautifully. I.have postponed my engine build until this one blows.....could be a while.

 

I would suspect that mine would blow at the track. Which is the way I'd want it.

 

^This.


I can feel when my oil is past 3k miles. The engine response is slower, power is down and it doesn't matter whether it is syn or conv. The oil is dirty at 3-4k and IMO needs to go. I just did mine last night at 4k and I knew it needed to be done 500 or more miles ago.

 

I know what you mean. Whenever it has been a while since I've waxed my car performance goes to heck and it is very noticeable. Same thing when the wiper fluid is low or old.

Seriously, some of you guys are nuts about the oil and oil changes. And the truth is that you've bought into the marketing hype and multiplied it by two. While it will never hurt your car to change the oil at ridiculously low intervals for ridiculous (and borderline delusional) reasons, there is no science or logic or practical value behind it.

 

Have you done alot of engine rebuilds or mechanical work ? I have seen many problems from people not changing oil regualarly or even regularly with oil from bulk oil change places like dealerships. Main problem I see from engines that people that think frequent oil changes are over rated are noisey lifters, especially from convention oil users. The oil does actually start to solidify in the lifter eventually causing it to not fully expand. They have very small oil passages and very very tight clearances that must stay clean for proper expansion to occur.

The other problem is that oils use a viscosity modifier that changes the oil's viscosity based on temperature. These chemicals brake down eventually and the oil will not thicken up at engine operatiing temperature. For instance in 5W-30 the higher the number the more viscous the fluid(thicker), W is for winter . So when it is cold the viscosity is 5(thin), when the engine heats up the viscosity is 30 which is what you need for protection for bearings. Once the oil breaks down it will be a 5 viscosity at all temps and your bearings will not have the correct protection especially with spirited driving. Without the proper viscosity in your oil your bearings will clash with your crankshaft and effectly wear it out prematurely.

I highly doubt you would feel any power difference from changing oil, probably just in your head because you have taken care of your car.

 

No company told me to change when I do. In fact, they've done the opposite. They've told me to buy their longer service oils and replace it less often.

Simple physics and chemistry tells me that power loss will come from dirtier oil because it is filling up with contaminants and causing my motor to work harder. My butt dyno feels a difference after an oil change and many dyno shops recommend fresh oil because it does help numbers. Increased friction will rob ponies in the end.

I'm OCD about my car's mechanical condition. 5k isn't a bad change interval but it isn't for me.

 

I've never done a rebuild but I've done a fair share of mechanical work. Mostly external stuff like carbs, headers and such. But that's not really the point is it?

I never suggested that changing at intervals that were too long was okay. If you go too long then it is TOO long. If you use bad oil then its BAD oil. I'm saying that it is not necessary in most cases to change your oil at 3500 miles, much less doing it that often with a synthetic. Again, the G35 owner's manual says every 7500 miles unless you make short trips, make long slow drives, tow a trailer, drive on dusty roads, etc. That does describe the way many of us use our cars but then the interval is 3750 and doing it more often than that, especially with a synthetic is simply a waste of time, oil and money. There is no data anywhere to suggest otherwise.

I don't care if someone wants to change their oil after every trip to the corner market for tampons, but don't try to sell that as anything useful or beneficial to the engine.

 

Obviously. But don't stop there. Google DSM IV.

 

I just bought my rev-up about 2 weeks ago, i have put about 1600 miles on it and it hasn't seemed to burn oil. I hope it stays this way.

I run conventional because that is what the previous owner said Infiniti told him to run.

 

That is my point, I have seen the inside of engines with all different mileages for rebuilds, lash adjustments, etc. and have witnessed first hand the differences in synthetic, name brand non-synthetic, and bulk non-synthetic(without detergents) that people have either done regular or slacked oil changes and the differences are staggering. I've seen the exact same Camry four cylinder cams with bulk Toyota oil changes(at 3K) being gunked to hell with rounded cam lobes and lifter tap and a always synthetic(3K) top end be shiny clean with no wear with the same mileaged engine.

You should also consider that the manufacturers that are recommending you change your oil every 7500 miles are in the buisiness of selling you New cars and want your future purchases sooner than later. Also motor changes at Infinity/Nissan dealerships help rake in the $ as long as gets out of warranty and isn't covered by a recall.

I do agree 3750 miles on synthetic should be fine(as long as it's not force inducted) but like me alot of the G's use a bit of oil so adding another half quart for 750 miles and just changing it is almost a wash. I usually buy a single quart for topping off which lasts about two oil changes, also Texas is damn hot sometimes so I just change it at 3K. In the winter I have went to 4K. I also only use expensive filters like Wix or K@N and use them for two oil changes(non-turbo), just remove them while draining the oil , shake out the excess and re-install. Expensive filters have better check valves that prevent drain back to help eleminate dry starts.

Another factor I failed to mention is carbon deposits and seals. If you have ever bought a used car and started using synthetic and have the engine start leaking this is most likely why. Those hydrocarbons that build up in your oil will start to cause carbon deposits to build up in between your cam/crank seals(even rubber valve cover gaskets), this is especially true with bulk oil because it lacks detergents. Once you switch that new(used) car of yours to synthetic or even a name brand non-syn depending on the lack of maintaince you will wash away those carbon deposits leaving a gap between the seals and their mating surfaces causing leaks.