Oil Filter Choice

[chasracer]

Just wondering what the preferred oil filter selection would be for the G-35?

I have been using Wix units for about 20 years and have had excellent service from them.

[awdjdmtalon]

Wix is a VERY good filter. I have cut open a wix and a fram. And the differance is amazing. The wix is so much better constructed. I personaly use Nissan filters. But I am a tech and belive in using OE parts.

[joe603]

+1 on Wix. I used to use NAPA Ultraguard gold filters (which I believe is the same as Wix)...but now I'm using OEM Nissan filters.

[awdjdmtalon]

you are correct. Napa Gold filters are Wix

[chasracer]

Not having checked out an OEM filter, what reason(s) would you have to use them?

On American cars, the OEMs can be some of the worse filters you could possibly purchase as most of them are farmed out to independent manufacturers with minimum requirements.

I noticed that there is a slightly larger filter available for the engine from Wix too. Looks to be 3/4" to 1" longer.

[chasracer]

Bump, funny but no one answered.

Here's some information for you if you would like to increase your filtering capacity by about 50%.

The part numbers that are listed for our G35 engines in a Napa Gold is 1365, the Wix number is 51365. Both filters are 100% identical as I have cut both open.

To increase your filtering by about 50% (just a guess judging by the increased filter size) pick up part number 1356 for a Napa Gold or 51356 for a Wix. There's no problem with the increased size and it's a simple mod to perform. I also use this filter on my wife's '07 Murano.

[tollboothwilley]

i've heard some people don't use the different size because of the extra strain it can cause on the oil pump??

In any case, thanks for the heads up.

[chasracer]

[QUOTE=tollboothwilley]i've heard some people don't use the different size because of the extra strain it can cause on the oil pump??

In any case, thanks for the heads up.[/QUOTE

Sorry, but sounds like someone is just making something up to me. Think about it, the oil pump pumps oil to whatever pressure its relief valve is set too. Does it matter whether it pumps it through a filter 3 inches in length or one that is 5 inches? I hardly think so, its just moving a fluid. On small block Chevy motors, its been common to switch to a two quart filter in some hi-perf situations from even the standard 1/2 quart unit and there's no ill effects.

[SVTCOBRA]

I only use Nissan filters.If I were to use another it would be WIX from Napa.I do use WIX air filters $4.50 vs $19 for NISSAN....Also use a K&N air in the coupe.

Have heard nothing but bad thing about fram

[pfarmer]

i've heard some people don't use the different size because of the extra strain it can cause on the oil pump??

In any case, thanks for the heads up.[/QUOTE

Sorry, but sounds like someone is just making something up to me. Think about it, the oil pump pumps oil to whatever pressure its relief valve is set too. Does it matter whether it pumps it through a filter 3 inches in length or one that is 5 inches? I hardly think so, its just moving a fluid. On small block Chevy motors, its been common to switch to a two quart filter in some hi-perf situations from even the standard 1/2 quart unit and there's no ill effects.

Actually I think it may make a difference, but most likely in a positive way. It depends if the relief valve is a full flow relief valve or one that simply trims the rest of the system it was designed for. If the filter is the restrictive factor compared to the rest of the nozzles (for example timing chain) or other orifices, then a larger filter would tend to be less restrictive and you may gain some flow to the system.

Perry

[awdjdmtalon]

I actually use the bigger filter for the VQ40 in the Xterra. The extra capacity for filtration is always a good thing. Like was mentioned earlier about the Chevy guys using the 1 quart or bigger filters on race cars.

Next time I change my oil, I will try and remember to cut open a stock filter to see how it is constructed.

[pfarmer]

I actually use the bigger filter for the VQ40 in the Xterra. The extra capacity for filtration is always a good thing. Like was mentioned earlier about the Chevy guys using the 1 quart or bigger filters on race cars.

Next time I change my oil, I will try and remember to cut open a stock filter to see how it is constructed.

Two features, one is very common, should be present. You should have a bypass for when the filter is plugging off and you should have a device to prevent the system from completely draining when shut off (anti-drain back).

A larger filter in most cases I believe is a good thing. You have the filtrations surface area. This may translate into a lower resistance to flow since it takes place over a larger area. The filter can hold more dirt so it can last longer before bypassing. It holds more oil than the smaller stock filter which increase you total oil capacity. There is some cooling advantage for larger filters due to surface area.

Because the oil pump is a positive displacement pump I see not disadvantages with the larger filter all else being equal.

Perry

[chasracer]

I think you need to be very careful when looking at bypass valves in regard to filters. In some cases (poor designs) a bypass valve can close off at such a low pressure number that you essentially are never really filtering the oil as the normal pressure for the system exceeds that of the filter's setting. Again using the Chevy as an example, the oil bypass valve is built into the oil filter adapter. In as long as you are using a top notch filter and pay attention to not over-revving the engine while the oil is cold, almost anyone using these engines in a high-performance role blocks off that bypass valve to ensure that the oil is always being filtered.

I am not yet that familiar with the Nissan engine so I am not sure about the bypass valve location nor the normal setting for it closing. Can anyone fill me in?

[pfarmer]

I think you need to be very careful when looking at bypass valves in regard to filters. In some cases (poor designs) a bypass valve can close off at such a low pressure number that you essentially are never really filtering the oil as the normal pressure for the system exceeds that of the filter's setting. Again using the Chevy as an example, the oil bypass valve is built into the oil filter adapter. In as long as you are using a top notch filter and pay attention to not over-revving the engine while the oil is cold, almost anyone using these engines in a high-performance role blocks off that bypass valve to ensure that the oil is always being filtered.

I am not yet that familiar with the Nissan engine so I am not sure about the bypass valve location nor the normal setting for it closing. Can anyone fill me in?

I am not sure about the location on the 'G' in the filter or outside, but I believe it is a feature that should be present on a street car. The factor about oil being cold and not passing through the filter is one reason for the bypass valve in a street car where you do not know where the car is going to be driven (looking at this from the manufacturer's side of the tracks).

Those who race do in fact know where they are and take the precautions necessary like you said. Also as you mention if it is located in the filter you do want a high quality filter.

What many may not realize is that while it seems to always be stated that this is for engine lubrication (which it is) it is rarely stated about oil pump protection. Nearly all positive displacement pumps should have a guaranteed amount of flow. One reason is lubrication for the pump itself due to its design. Positive displacement pumps should not be dead headed.

Because of these two factors when you see similar pumps in industries they often have two trips associated with them. A low pressure trip associated with the equipment being supplied and a high pressure trip associated with pump protection. I image that these two factors are taken into account by race car drivers and for these same reasons. But for a normal street car with normal street drivers I would never have a design without these protections built in.

In the case of the anti-drain back feature one issue can come into play and that is it is often absent in filters without bypass valves.

To me this is one reason to go with an oil cooler as you can select a high quality filter without either feature but have these protections supplied in other ways such as in the adapter or external of the adapter. In the case of the bypass you can actually have a manual valve to disable the feature when racing and enable it for street use of the same car. The anti drain back is a good feature especially in autos prone to piston slap on startup, very common in some Chevys, many Fords, and from what I see more than a few Infinitis. Many mistake the noise they hear for valve train noise when in fact it is piston slap.

Perry

[chasracer]

I am not sure you understood my point concerning oil bypass valves and since no one else chimed in on the subject, my thinking is that the majority out there do not understand them either.

So....

As an example, let us say that the bypass valve has a setting of opening at 35 PSI and your normal idle to 45 mph speed keeps a fairly constant 30 PSI of oil pressure. All is right with the world, the oil is being filtered as we intended. This is of course with a fresh filter too. Now as we accelerate for that assault on the Interstate system and climb into the 70+ mph range, our oil pressure has risen due to the increase in RPM to a nice round 42 PSI. Well, guess what folks, your oil filter is now just along for the ride. The bypass closed off 7 PSI ago and isn't going to open again until the pressure on the system drops to 35 PSI or lower. And as your filter ages, collects more debris, it increasingly raises the pressure on the entire system, to the point where you might not even make it to that nice 45 mph cruise speed with the oil filter open. I also should state that this is a very high level view of an oiling system, most of the time you will see quite a bit of variation in oil pressure if you were to monitor it with a really good gauge and therefore that bypass valve can be opening and closing rather often.

Now, before everyone gets alarmed about this, the engineers that built the car and the manufacturers that made it understand that the filter only actually filters oil part of the time. It's one of the reasons why you will see a recommendation from many manufacturers to only change the filter every other oil change! Now, most car enthusiast are not going to leave a quart of dirty oil in the mix when they make a change and of course for the cost of the filter, time, etc, it is cheap insurance.

Back to my original thread topic, you can very easily increase the capacity of your filtration by moving up to the larger filter and for all of the reasons mentioned before, it is a good move. Assuming that everyone here has actually changed their own oil, you know that the standard size filter holds maybe a pint of oil so any increase is going to be welcome. If I have one gripe it is the increased cost of filters! My last trip netted me 4 filters at a cost of $28.00, the darn things were about $4 just last year. Another rip-off.

[pfarmer]

I am not sure you understood my point concerning oil bypass valves and since no one else chimed in on the subject, my thinking is that the majority out there do not understand them either.

I understood it. I just disagree that for most street users it is a large issue. What is also important is that typically you also have a pressure relief valve as well.

With a quality filter you should be filtering oil the majority of the time which is better than not supplying filtered oil at all or have a condition where the pressure on the filter exceeds the capabilities of the filter. Though rare for street user more than a few who race have exceeded the burst pressure and suffer the results. On many filters the burst pressure is as high as 400 psi. One design factor is that of the gasket, the filter may not burst but the gasket doesn't stay sealed.

For racing this is a different issue as the driver is watching for both conditions, high and low oil pressure. Many who use external coolers go with an external bypass valve but do so with one that can be isolated while racing. One advantage here is the quality of the bypass valve is such that it is more reliable and can be set. Another advantage is that it is easy to put an indication for filter bypass in the system on the drain line.

Actually most oil filters bypass valves start to open at around 8 + lbs. and at fully open at around 11+ lbs. (this range varies with application). Some VWs and Subarus use filters with differential settings of 30-35 psid. This is a differential pressure based on oil pressure before and after the filter. This is normally not a set system oil pressure setpoint like the oil pump relief valve. While true that a rapid acceleration will often force open a bypass valve it is also true that it will close once more. Also the typical bypass valve while in bypass mode is sharing flow with the filter until the fully open or fully closed position.

As system pressure rises the differential pressure will also rise. The concept of the bypass valve in a 'quality' filter is that over the normal life of the filter the normal operating pressure of the system will not cause the filter to bypass oil. While your pressure rise to 70 mph may open the bypass during acceleration, the steady state pressure at 70 mph is such that the filter should now have its bypass valve close as the now higher design supply pressure equalizes. There are some of course who decide to help their system along and increase the setting of the oil pump relief valve.

A couple of conditions will operate the bypass valve, one of which is very cold temperatures will cause a filter to bypass until the oil is warm, the other is rapid rises in oil pressure (ie rapid acceleration), another factor of course is a plugged filter.

With a larger filter you can hold a lot more debris. A small filter on some vehicles can hold as little as 20 grams where as a larger filter can hold proportionately more based on its increased media surface area. If a bypass valve is present the valve will typically open later on the larger filter even with the same bypass valve setting.

While I am not aware of one for Nissans, a few here probably could benefit from the use of full time bypass filters versuse full flows for the better filtration benefits.

Perry

Modified by pfarmer at 2:23 AM 5/30/2009
Modified by pfarmer at 2:27 AM 5/30/2009

[chasracer]

I understood it. I just disagree that for most street users it is a large issue. What is also important is that typically you also have a pressure relief valve as well.

Correct and I should have stated that the numbers that I was using were to only demonstrate a specific point.

One point that I do not agree with you on is the differential pressure treatment as it sounds correct in theory and in some systems I am sure it reacts just as you stated, but the dynamics of fluid follow certain rules, one of which is the path of least resistance. When a bypass valve opens in the typical oiling system, I have seen time and time again that the filter is effectively bypassed and what little if any oil is flowing through it is certainly not going to save damage to an engine. I do have some very expensive proof of this happening in the past to me. One item that I want to make people aware of is moving to an aftermarket remote filter setup. While this may have a race inspired look to it, it is very important that the person understand that the type of filters used in these setups will quite often have an internal bypass valve which is actually what you do not want in your system.

Overall I do agree with you that for the most part, no one is going to lose an engine in as long as they follow a decent maintenance schedule and use quality products. I honestly cannot remember which oil vendor is doing it, but I just heard the recent ad about a 300,000 mile engine guarantee and had to laugh. First, although things are changing today it would be doubtful to see someone hold on to their current ride for that long and second, if again you are using quality products and following a decent schedule, something other than an oil related issue is probably going to be the demise of the engine. Good stuff and thanks for the conversation!

[dougiefresh7988]

another good choice for you buddy is k&n oil filters you can pick up at any local auto part store. i have been using them in my o5 g35x sedan and it runs awesome and i had a 95 maxima and that was all i used and it ran awesome until i sold it @ 210,000 miles .

[pfarmer]

Correct and I should have stated that the numbers that I was using were to only demonstrate a specific point.

One point that I do not agree with you on is the differential pressure treatment as it sounds correct in theory and in some systems I am sure it reacts just as you stated, but the dynamics of fluid follow certain rules, one of which is the path of least resistance. When a bypass valve opens in the typical oiling system, I have seen time and time again that the filter is effectively bypassed and what little if any oil is flowing through it is certainly not going to save damage to an engine. I do have some very expensive proof of this happening in the past to me. One item that I want to make people aware of is moving to an aftermarket remote filter setup. While this may have a race inspired look to it, it is very important that the person understand that the type of filters used in these setups will quite often have an internal bypass valve which is actually what you do not want in your system.

Overall I do agree with you that for the most part, no one is going to lose an engine in as long as they follow a decent maintenance schedule and use quality products. I honestly cannot remember which oil vendor is doing it, but I just heard the recent ad about a 300,000 mile engine guarantee and had to laugh. First, although things are changing today it would be doubtful to see someone hold on to their current ride for that long and second, if again you are using quality products and following a decent schedule, something other than an oil related issue is probably going to be the demise of the engine. Good stuff and thanks for the conversation!

The reason why the flow is shared is the fact that the oil pressure is equalized on the inlet side of the flow and on the outlet side of the flow and therefore is dependant on the bypass opening position which is variable based on differential pressure. It will not of course be linear as valves generally do not have linear flow patterns. Fluid dynamics in this situation can be thought of the same as ohms law for dc circuits. As one resistance in a resistor pair goes up the greater flow will be in the lowest resistance resistor. The difference using ohms law as an example is the fact that the bypass valve does not have linear flow characteristics. Depending on valve design many have most of their throttling between about 20-60 percent positions. Below 20 percent many valve designs are essentially closed, above 60 percent essentially open.

As far as a little oil flowing through a filter not saving an engine, well no oil flowing to the engine is not going to save the engine and hastened its failure.

Another filter type not mentioned which I hinted at above is the partial bypass filter versus the typical full flow filter (not to be confused with full flow filters with bypass valves).

While typically not used much (they are used however) in automotive applications they have found favor in industrial applications that are at least as critical and similar in nature. Basically in a partial bypass filter some oil is always bypassed. This allows the filter medium to catch much finer particals than a full flow filter. The disadvantage is that what starts out as a fairly small failure can cascade into a catastrophic failure. Schemes are often in place to pick this up as it is occurring and placing a secondary filter automatically in service.

Why did I mention this? Because a full flow filter that is in partial bypass mode has the same characteristics with the exception of capacity. With an external oil cooler and filter this is an easy setup since the bypass valve can be separate from the filter with dash indication when it is operating.

Now as far as 300 k miles. I have achieved this and the only reason I got rid of vehicles in this area were other non-engine related factors that came into play. And these were no where as sophisticated of engines as the Infiniti. In fact that was one reason I purchased the Infiniti. My idea was that I wanted a car that could travel at double the speed limit since at the speed limit it was likely to be very reliable. While many can achieve this high limit (I was looking at 150 for a number) most I was interested in did not have the reliability ratings of Infinitis. I personally believe the engine is capable of probably reaching close to the 5 century mark if treated well.

Perry