I bought my 03 G35 6MT with about 45k miles on it in May 06-- i think the previous owner used regular oil. First time i changed the oil, i switched to Mobil 1 5w-30 and have been using it since (im at 70k miles now).

I don't remember when, but i started getting warnings on my navi that my car had 'low oil pressure' (and the oil light would light up on the instrument cluster) -- it would only happen when i took a turn into a parking space really fast or something, or pull a u-turn really quickly. next time i took it to nissan for an oil change, i asked and they said it was probably because the oil was just low, and it triggered that warning when i took a sharp turn because the oil splashed to one side of the container, and tripped the pressure warning.

anyway, so id tend to get the warning a bit before id hit the 5k mile mark (thats how often i change my synthetic), so id just do the oil change a little early, problem solved.

but lately, the last few months... ive been getting the warning frequently and ive just been adding quarts of oil. but ive been getting concerned, bc ive literally started getting the warning so often that ive had to add a quart, and then 3 weeks later ive gotten the warning again, added more oil, etc. it seems like its just coming more and more frequently these days.

when i took the car into infiniti for my 65k service, the advisor said 'are you sure you want synthetic? this car burns synthetic like there's no tomorrow, so we don't recommend it'

so i'm curious to know if others have had a similar experience, and if anyone has (or just knows a lot about this) can speak to whether this is just normal for synthetic oil in our cars... or if it sounds like there might actually be a leak or something. if it's normal for synthetic.. should i switch back to regular oil? or is that a bad idea?

i'd appreciate any thoughts/recommendations!

 

ive heard that syn is sometimes to good, and that since r motors are known for blowby it might be easier for syn to pass thru.

 

You had this problem when you bought the car, you just didn't know it. Once an engine is allowed to run down to less than 2 qts of oil (the only way it will flash the warning), the damage is already done. From there it just gets worse. If you plan to keep this car, you must check the oil every day for a month to set the "base line" for oil consumption. Then you will have a better understanding of how much oil it will use. Then you MUST keep it full, never let it fall below one qt low (lower hash mark on stick) or it will only increase until the inevitable happens.

 

what damage are you saying might have been caused (im not sure what you meant by 'inevitable'). is there something i should do to reverse the damage?

so other than make sure im never low on oil, what should i do from here on out?

as i asked, should i switch back to regular oil?

 

That's about all you can do.

Synthetic oil is fine, but if you are using it up at a heavy rate, you might as well use dino oil, it's cheaper.

When the oil gets real low, it can't do the work of a full 5 qts of oil. It over heats and breaks down quickly. Then your rings and valve guides go next. The cylinder walls are scored (remember, this is a nicasil sprayed lining on the cylinder walls, not good ol' cast steel or iron. Oil is the lifeblood of a motor. You must treat it well and change it often.

Also, resist the temptation to NOT change your oil on a regular basis because you are adding it at a rapid rate. You must flush out all the contaminants with an oil change at the regular intervals. Just adding a quart or two leaves all the acids and water and metal shavings in the pan.

As for the inevitable remark, I was referring to the eventual rebuild of the motor due to oil use.

You may want to search this forum on oil consumption, there are many threads on it. Some of these motors are known oil users and it's not from a lack of checking it. There is even a Technical Service Bulletin on it.

 

Don't you actually check your oil level vs waiting until over half of it is gone? Might help.

 

Yes you should. Level ground, hot motor, ten minutes, wipe the stick and insert fully. EVERY DAY until you find out how much it's using.

 

I hate to say it, but just sell or trade it. The 6MT motors are more prone to this, especially the revups. It's a common problem that doesn't just go away. If anything, it will get worse over time and you are out of warantee.

 

so there's nothing i can do? basically, i'm screwed and the only thing i can do is make sure i have enough oil between now and the time my car will inevitably DIE bc of unreversible damage?

in addition to that general question, can someone let me know their thoughts on switching back to regular oil so i don't burn so much??

 

bump now im getting really nervous about this

 

It's a myth that going back to dino will reduce usage, or that synthetic oils get consumed faster. The main things influencing whether an oil will be "consumed" are it's viscosity and volatility index. The things you can do in the meantime if your engine is using excessive oil is to bump the viscosity a grade and use a low volatility formulation. Usually these are the turbo-diesel rated oils due to high temps, compression, and bearing loads. Try this and see how your usage does.
http://www.mobil.com/USA-English/Lub...ruck_5W-40.asp

Before you do, you should have the compression checked on all cylinders as a baseline to see how it does after the change to the turbodiesel oil.

 

That sucks man.

 

i just talked to my SA at Infiniti -- he said i should go back to reg oil because synthetic is *known* to burn through really fast on our cars, and he said i should put in 10W-30 rather than 5W-30. He said I should have a compression test done to see if there's damage (he quoted me around $300). Should I have this done-- is it worth all that just to know? And can i get a compression test cheaper?

I also asked the guy at Kragen about the truck diesel oil idea, and he strongly recommended against doing it .... you sure it's a good idea?

Anyone have thoughts on my predicament?

 

It depends on WHEN. If the majority of the oil is getting burn AFTER the oil is warm, then switching to a 10w-30 vs a 5W-30 won't accomplish squat. If most of the oil is burnt during warm up, then yes, that MIGHT do something.

You can get a compression checks for less than $300.

 

I've been running the Mobil 1 turbodiesel truck 5W/40 for over 30000 miles and the car runs perfect with very little oil consumption. The guy at Kragen probably doesn't know that the Mobil turbodiesel oils are fully API rated for gasoline engines as well. In fact, they contain a much more robust additive package for the same price. Oil types are all about marketing. I run it to 15K miles and my oil analysis has been good with plenty of TBN remaining even after 15K miles. Of course, I have a 4X bigger remote filter too. Don't try to run 15K miles using the stock oil filter or the flow will drop to the point of bypass.