Advice for next oil change on '04 Infiniti G35.

[OCDriver]

I've been getting so much differing advice about my next oil change, my head is spinning

I have an '04 Infiniti G35 I purchased about a year ago, it's just clicked over 155,000 km (~97,000 mi). For my first oil change 4,400 km ago (~2,700 mi), I put in Mobil1 5w30 full synthetic.

I've been needing to add about 250mL every 1000km (roughly 1/4 of a quart per 620 mi). I have checked everywhere for leaks; they are not be found. The bottom of the oil sump, drain plug, filter, filter ring, under-shroud... all dry as a bone. They don't even *smell* of oil. There are no puddles on the floor. I've also never seen blue or any other discoloured smoke from the exhaust. I plan to check the PCV valve today, but I don't know what to look for after that. I've done a bunch of reading up on this, and oil consumption seems to be a very common issue with this car due mostly to under-engineered piston rings causing excessive blow-by. I check the oil religiously and top it up when needed.

While I've seen the oil level consistently go down, there have been no other symptoms. The engine runs well, pulls hard, there are no major operating problems with it. But I know any oil burning can't be good for the combustion chambers long-term if it's diluting the fuel mixture. So, I'm trying to do what I can to reduce the oil consumption while still using an appropriate oil that will allow this engine to run for a long time.

There's a ton of, "this is what I use, you should use it too", etc. One guy thinks that I should never use synthetic in this engine because of the known oil consumption issues, another guy tells me I should use nothing but synthetic or I'll wreck the timing chain, others say "whatever" as long as it's quality oil of the right viscosity.

I've considered and been recommended pretty well every possible variation:

• plain old conventional (molecules are less uniform, less burn-off?)
• higher viscosity full synthetic (concern over increased oil pressure in high mileage engine?)
• 0w40 full synthetic (better for cold starts?)
• high mileage full synthetic (will the seal swellers and additives be enough on their own?)
• high mileage synthetic blend (a good compromise or insufficient protection?)

I don't track the car. I always let it idle for a minute on cold starts and drive gently while it gets to operating temp, but I do like to wind it up quite a bit when it's warm. Can I really go wrong as long as I stick with the right viscosity and get a quality oil with both API donuts?

What say ye, experts of BitOG?

 

[Garak]

Your consumption isn't that high. It's not great, but it's fairly reasonable. If you want to try a thicker synthetic without breaking the bank, go to Imperial Oil and grab the Delvac 1 that's in my signature, or Delvac 1 LE 5w-30. It's worth a shot. At the very least, it might save you some money in the long run, since it's cheaper than most store bought stuff in Canada.

And, you are right. You cannot really go wrong as long as you stick with the right viscosity with the correct service classification.

 

[KGMtech]

try with the continued use of the M1 synthetic. Your engine MIGHT have slightly plugged oil return holes at the oil control rings of the pistons. Repeated use of a good oil with slightly shorter interval will clean this area up - if in fact this is a problem.

Either way, it won't damage anything other than your wallet )

As stated, the consumption you show is not really extreme, nothing to loose sleep over.

 

[OCDriver]

Thanks for the replies. Cost of oil is not much of a concern for me. I only put on 5,000 - 8,000 KMs per year, so my OCI only comes around once or twice a year; I'll spend whatever I need to on oil to be sure it's the right stuff.

 

[mazdamonky]

I would try an HDEO 5w40. It is hard for me to imagine the engine wouldn't like it.

These engines are known to experience oil consumption. It seems like a nonissue to me. Many engines burn more. Burning through 1 quart every 4k KM isn't much at all. I wouldn't fret it. The only negative effect of oil in the combustion chamber is carbon buildup which can be resolved by driving the car like it was designed to and hit the upper rpm a couple times a week.

I would probably use a decent quality Synthetic or semisynthetic in the recommended weight or a synthetic 5w40/0w40. You might like something A3/B3 or A3/B4 rated such as castrol 0w40 pennzoil 5w40.

Timing chains tend to be a little harder on oil which is why i recommend a blend or full synthetic. But I imagine some PYB was never the cause of death of an VQ engine.

 

[CATERHAM]

As others have mentioned your oil consumption is not anything to be concerned about nor to try and remedy.

And a 0W-40 is not lighter than the 5W-30 you're using on start-up unless it's extremely cold and then you'd still be better off using a 0W-30.

 

[OCDriver]

Is there any warrant to the notion that a 40 on the hot end may be over-stressing on a high KM engine?

 

[il_signore97]

Originally Posted By: OCDriver
Is there any warrant to the notion that a 40 on the hot end may be over-stressing on a high KM engine?


To answer your question: Not at all...

I owned a Nissan VQ-powered vehicle for 8 years, and they are nice engines, but can be hard on oil and do have specific issues to watch for (as I'm sure you already know about).

If you look at the owner's manual, you will see that up to a 10W40 is perfectly acceptable and formally "allowed" by Nissan for this engine (not that you need their permission to use it!).

I would use a high quality European style 0W40 in that engine without issue (as I did for most of the latter half of my ownership with the VQ engine). A 0W40 will serve you in any weather condition without issue. The higher HTHS will help when engine oil temperatures rise (which this engine family is known for) while being driven spiritedly. Alternatively, as Garak suggested, his use of Delvac 1 5W40 is also totally fine. Your choice (depending on whether or not you actually need a "0W" or not, and depending on economic reasons). Personally, I am content buying Castrol 0W40 at Canadian Tire when it goes on sale for 28-30 bucks for 5L (or for 4.4L of Mobil 1 0W40 when it's on sale).

 

[OCDriver]

I'm in Manitoba, so that means -30 winters and +30 summers. Although 5w30 starts easily with enough time on the block heater, that wide temperature range makes 0w40 a very attractive option to me.

Is my understanding correct, 0 will lubricate faster on cold starts and make it's way up to 40 as the engine warms?

And I would be able to run that oil all year long?

 

[OCDriver]

Originally Posted By: OCDriver
Is my understanding correct, 0 will lubricate faster on cold starts and make it's way up to 40 as the engine warms?


Upon further reading, I think that's probably incorrect. It just means that it retains it's rated viscosity index of 40 at lower temperatures than, say a 5w40 would. Right?

 

[Shannow]

Not quite.

In (overly simplistic) terms the engine will crank as well and the oil flow into the pump pick-up as well at -35C as a 5W oil will at -30C, and a 10W at -25C.

That's how readily the engine turns over, and how easily the oil gets to the pickup.

The "0W" doesn't mean anything other than that...running a "0W" at -10C because it "flows better" being a "0W" is wrong.

 

[Garak]

And yes, you could run a 0w-40 all year round. The same would apply to just about any 0w-30 you could choose that would make sense in that engine, including an ILSAC 0w-30 or even something like GC.

 

[OCDriver]

Oh, I forgot to mention, I typically make a lot of short trips. Small town, so only a 5-10 minutes of run time. Would it be better to stay with a 30 then or is the Xw the more important number then?

Still trying to fully wrap my head around how to properly interpret oil viscosity.

 

[il_signore97]

Originally Posted By: OCDriver
I'm in Manitoba, so that means -30 winters and +30 summers. Although 5w30 starts easily with enough time on the block heater, that wide temperature range makes 0w40 a very attractive option to me.

Is my understanding correct, 0 will lubricate faster on cold starts and make it's way up to 40 as the engine warms?

And I would be able to run that oil all year long?



To show you how this question gets answered, and also to add to the great info that Shannow and Garak already provided you in this thread, here is some more specific info on how the oil grades are determined:

The latter number in the grade (i.e. 20, 30, 40, 50, etc) is primarily determined by one factor: kinematic viscosity (cSt) at 100 C. So for example, for an oil to be called a 30 grade, it's viscosity must be between 9.3 and 12.4 cSt (inclusive). A 40 grade would be between 12.5 and 16.2 cSt.

There is also one further requirement for each oil grade. This is called HTHS (high temperature / high shear) viscosity, and is measured in units of dynamic viscosity (cP) at 150 C. So this number is not directly comparable to the kinematic viscosity as discussed above. It is meant to simulate the high shear conditions within an engine bearing, as the kinematic viscosity discussed previously is not measured under any shear (which is not really a good indicator of how thick the oil will appear to be in an engine bearing or in between a moving piston ring and bore). A 30 grade must have an HTHS viscosity (measured at 150 C) of 2.9 cP or greater. For any "European-style" 40 grade that meets ACEA A3/B4 specs (such as M1 0W40 or Castrol 0W40), this value will be 3.5 cP or greater. Basically, HTHS tells you how must viscosity the oil will "maintain" under very high shear and high temperature conditions.

Now for the low temperature stuff... As Shannow pointed out, the tests that determine whether an oil will be a 0W, 5W, 10W, etc are done at different temperatures. To ensure a level playing field, any oil must be labelled according to the lowest temperature test that it passes (so for example, if an oil passes the 0W test, it cannot be labelled as a 5W even though it also passes that test).

This test has two parameters: Cold Crank Simulator and Mini-Rotary Viscometer (both measured in dynamic viscosity, cP). The CCS test simulates how well your engine can turn over (crank) with a particular oil at a particular temperature (high shear conditions). The MRV simulates how well an oil can flow under it's own ability to your oil pump so that it can be sent to different parts of the engine (low shear conditions). Both are important, but in my opinion, MRV is paramount because if your engine starts, you would surely want to make sure that the oil has the ability to flow into your oil pump pick up tube in order to not starve the engine.

The tests are as follows:

0W must be below 6200 cP at -35 C for the CCS, and must be below 60,000 cP at -40 C for the MRV. Notice how the MRV is at a 5C colder temp. Also, it should be noted that 60,000 cP for the MRV is the SAE determined upper limit. Most military specs won't allow more than 30,000 cP in this same test.

A 5W passes the same tests, but will be below 6600 cP at -30, and 60,000 cP at -35 C. Notice that both temperatures are 5 C higher than those of the 0W. This trend continues for 10W, 15W, etc.

Having said all that, if you're regularly skirting around -30C, you're right on the limit for a 5W oil with respect to cranking ability. If you can, I'd air on the side of caution and go to a 0W. It may not be necessary, but might be helpful.

As for short trips (that you said in a post further down), there are two schools of thought. You can go thinner (30 grade) and get some fuel economy benefit due to the fact that your oil won't be warmed up fully, and you will be wasting power shearing the thick oil in your engine bearings. However, the other train of thought is that because you're short tripping in cold weather, your engine will most likely be running rich (excess fuel for proper combustion) for a fair amount of time. This dilutes the oil and thins it out over your change interval, and reduces its viscosity. It may or may not be a problem, but one easy way to counter this is to go up to a 40 grade. It could be thicker than necessary, but thicker will never hurt an engine, just waste a bit more fuel, that's all.

Hopefully that helps instead of confusing things more!

 

[ukmastermind]

How's your oil pressure? I was just reading a tech article about internal oil leaks on 3.5 & 4.0L VQ engines. First sign was irregular oil pressure and eventually oil warning lights

 

[ryanschillinger]

My 03 maxima has same engine. Uses a lot more oil. About a quart every 8-900 miles! It was always well maintained by previous owner. Uncle bought new, I'm 2nd owner. I installed a new pcv valve and oil catch can. It's caught some oil but not nearly as much as I'm losing. Must be rings or valve seals I guess? It always got 5w30 from dealer and most receipts found said mobil1 so not like it was neglected.

 

[OCDriver]

Wow, that is a ton of useful information to digest, thanks il_signore97! I'll have to read this a few times

Originally Posted By: ukmastermind
How's your oil pressure? I was just reading a tech article about internal oil leaks on 3.5 & 4.0L VQ engines. First sign was irregular oil pressure and eventually oil warning lights


My G is completely stock, so I have no oil pressure gauge, unfortunately, only a warning light. The light has never come on. I am thinking about having a gauge set installed for oil pressure and some other things (fuel pressure and actual thermostat readout, probably)

Originally Posted By: ryanschillinger
Must be rings or valve seals I guess?

Yeah, everything I've found seems to indicate under-engineered piston rings on these particular engines. Too bad, because they're otherwise awesome!

 

[dtownfb]

Like il_signore97 and ryanschillinger, I owned a 2004 Nissan Quest which has the same engine. They burn oil. That era (2003-06) was not good for the VQ engine. Honestly, I would use conventional 5W-30 and keep the oil changes at 3,750-4,000 miles. With this OCI, conventional oil will protect your car as well as synthetic for less cost. KEep an eye on the oil level. Running these engines on low oil will stress the timing chain.

Good luck.

 

[ukmastermind]

Nissan VQ Engines

Here's the article. Just an FYI for all VQ fans

 

[OCDriver]

Originally Posted By: ukmastermind
Nissan VQ Engines

Here's the article. Just an FYI for all VQ fans


Interesting read. Question though... if there were an internal leak and no external evidence of a leak anywhere, where is it going? Draining into the sump and burning through the PCV system?