Ok, first off, I did a search... from what I found(roughly):

25% of the posters run 5w-30 conv. oil

25% of the posters run 5w-30 syn. oil

25% of the posters use 10w30 conv. oil

the remaining 25%, 10w-30 syn. oil

Everyone thinks that all those doing anything other than what they're doing is an idiot.

So the question is... what oil to use... I found no real answer searching, perhaps I can get some replys just telling me what you use with out turning this into a syn vs. conv debate. Otherwise I think I'll run some 0w-95 synthetic blend with like two tablespoons of lard thrown in just to cover all my bases...
MV

Mobil1 10w30 spring/summer oil changes
Mobil1 5w30 fall/winter oil changes

Look down a couple of threads and you will see why. I don't care to spend $1200 for a short block.

I think you're on the right track, there Ruger. I'd up the lard to a half cup, though. Better lubrication for the top end...

:rolleyes:

I use Valvoline SynPower 10W30 synthetic & here's why:

Valvoline - because it's a name brand and one of my friends thinks its better... my advice is just to use a major (ie: non-cheapie) brand.... Mobil, Valvoline, Quaker State... not Bob's Oil.

10W30 - because I live in Texas where it gets damn hot and I just don't feel comfortable with he thinness of 5W. They are both supposed to behave like 30W at high temps though... so 5W is really probably the more intelligent choice. 10W30 or 10W40 are mentioned in my manual as OK as long as the temp isn't below 0F, but 5W30 is recommended for all temps.

Synthetic ... It's proven to be better. It's also proven to be more expensive... so make your own decision.

Oh, and the other unsupported opinion that I've heard from a few friends is that Fram filters are horrible quality. Is it true? Who knows... but thinking about this sort of thing made me start using genuine Nissan filters and parts... you KNOW that those are OK.

I use Mobil 5W30 dino oil. 5W30 because it's what the book says. Mobil because the mechanic I used to go to said it was good stuff. Dino because I've always used it and never had a problem. And always a Nissan filter.

In other words, I have no really good reason for any of this (except maybe the 5W30).

Ruger1022,
Heh, there are as many opinions about oil as there are people out there.

I'm running Schaeffer's 7000 5w30 which is a synthetic blend. My last oil analysis showed that the oil could go about 6000 miles between changes. I'm currently going about 4500-5000. There was a high percentage of insoluables (not high enough to be a concern yet, but high nonetheless) that might be attributable to the Nissan filter. I'm going to try a Hastings filter next to see if it does a better job of keeping junk in the filter.

I'd suggest 5w30 year round, unless you live in a hot area where 10w30 might be a better choice for the summer.

Dino vs Synth? Either should be fine...just keep in mind that most dino oils and some synth oils (Castrol Syntec specifically) start to lose their viability after 4000 miles or so.

Bogatyr

5W30 - what Nissan specs
Mobil 1 - Good stuff, can't hurt, doesn't really cost much, a whopping $15 more per change, *gasp*

Brent

I grew up in a business that built street rods & competition engines for a living. As a result, I spent a better part of my adult life in the motor sports community.

During the 1980s, I campaigned several successful H-Stock and SS/A cars in NHRA Div. 7 Competition, taking class wins in 1988 & 1989.

This exposure to engines and improving their performance, led me to do a number of experiments and studies relating to engine oils, gear lubricants and brake fluids.

I have written a number of technical articles on the subject of motor oils and decided to share some of the information with the members of this forum.

It is no secret that synthetic oils are more expensive than conventional oils. The question remains, is synthetic worth the added expense? The answer will depend largely on what your manufacturer recommends and your operating conditions.

The reason synthetic oils are more expensive is because of the refining process. The name synthetic means that it is chemically synthesized from different hydrocarbons. Engineers start with a hydrocarbon, then derive from it the gas ethylene, and then chemically synthesize that into the base stock for synthetic oil.

'Base Stock' is simply the oils post-refinement state prior to the addition of additives. In petroleum lubricant terms, this is often referred to as Bright Stock. In synthetic terminology, it is known as PAO or polyalphaolefin.

Premium additives also add to the cost and are beneficial for reducing friction, resisting oxidation and thermal breakdown, and eliminating sludge and varnish formation.

These additives also make the oil more thermally stable, meaning it doesn't change viscosity as much when subjected to high and low temperatures when directly compared to conventional oils.

So what does all that mean to you? Because the oil is synthesized from the same molecule, the molecules of the base stock (of synthetic oil) are all the same size and there are no impurities normally found in petroleum based oils.

This causes the synthetic oil to be more thermally and chemically stable, and will enable it do a better job of lubrication under all conditions.

when you heat the synthetic oil, it is less volatile, and when you freeze the oil it will pour when petroleum oil would be almost solid. Also, over extended use, the synthetic oil will retain the same lubricating quality longer.

In contrast, petroleum oil's molecules are of different sizes and shapes, and some of the molecules are undesirable.

Refining will remove most but not all of the impurities. The oil's viscosity and lubricating quality will change overtime because the smaller molecules will burn off. This process will also cause acids and sludge to form in the oil. Therefore, petroleum based oils should be changed at shorter intervals.

Whether or not you should use a synthetic oil is largely a matter of personal taste, but I will tell you a little about my experimentation while campaigning in NHRA Racing and building street & competition engines for the general public.

My partner and I raced the 429 Ford and the 440 Chrysler extensively in our racing days. Keeping an engine alive was important if you wanted to finish an event. To that end, we were always looking for that competitive edge.

This experimentation led us to adopt DOT 5 Silicone Brake Fluid in 1983 and I have used it in all my street cars since that time. I have never had any of the negative experiences you often read about this fluid, so I continue to use it.

It is not currently recommended for cars with anti-lock brake systems, but I have used it in Ferarri's with ABS and experienced good results.

The biggest advantage to Silicon Brake Fluid is it's ability to combat mositure, lubricate rubber seals and in general, make the entire system last longer. This is especially important for collector cars which see periods of extended storage.

For this reason it is extensively used in aircraft. The U.S. Army and U.S. Postal Service use this fluid exclusively.

For the average vehicel, you should use the fluid recommended by the manufacturer and change it at specified intevals.

With engine oils, we tried running synthetics and made the following observations.

Synthetics pump faster when cold and remain more stable when hot, but with the large (loose) clearances, as used in a competition engine, we noted lower overall oil pressure (grade for grade) when using synthetics.

This would make no difference in a street-driven vehicle and the pressure was still within what could be considered 'normal' limits, but because of the large (main & rod) bearing surfaces in the 429 and the high (7100 rpm) engine speeds, that oil pressure was critical to its operation.

We initially used Mobil 1, and later Amsoil, which was provided to us by a local speed shop free of charge.

We subjected this oil to a number of 'burn off' tests, where the oil was superheated until it caught fire, then recorded the temperatures at the oil's flash point.

When compared to conventional oils, the synthetic was far superior. It did not char or turn to tar when superheated. However, the temperatures at which this oil excels was sufficiently high enough to destroy an engine long before the oil stopped lubricating.

Although our engines were subjected to severe operating conditions, we did not run elevated operating temperatures.

Oil temperature is closely related to coolant temperature and will generally be 50° to 75° (F) above coolant temperature.

Ideally, engine oil lubricates best between 180° and 200° (F) and this would be considered by many chemists to be the oil's ideal operating range.

Oil should be kept under 220° (F) if possible and 250° to 275° is considered the high end of the scale. 300° (F) is also considered the 'breaking point' for conventional oils.

Our engines ran coolant temperatures of around 175° to 180° during competition events and oil temperatures were never recorded above 215° (F)

With rich mixtures, loose clearances, engine oil coolers and short drain intervals, I concluded that synthetic oil offered us no measurable benefit in a naturally aspirated racing engine. Even in a high-speed endurance application, if oil temperature can be controlled, the synthetic oil would offer little benefit.

So why do so many race teams use synthetics? The answer is actually quite simple. Many synthetic oil manufacturers, like Royal Purple, Amsoil and Redline, have sponsorship programs that provide oils free of charge in exchange for product endorsement. The same is true with tires, fuel, engine components and safety equipment.

There is certainly nothing wrong with a synthetic engine oil and there is no doubt it is superior to petroleum based oils, but will the benefit from this oil be realized in the average engine and will the added cost be offset? In certain circumstances, the answer is yes.

Newer automobiles are built with tighter clearances and different materials than ever before. The quest for ULEV (Ultra Low Emission Vehicle) certification by automobile manufacturers, drives air/fuel mixtures leaner and hotter than ever before. The trend toward high specific output (small high revving) engines and turbo charged / supercharged applications also change the environment engine oil must operate in.

Many newer automobiles come equipped with 200°(F) thermostats and routinely operate at coolant temperatures of 220°(F) or higher. Cars with turbo chargers run even higher oil temperatures.

All of us have stopped in the drive-through for a soda on a hot day. Think about the environment inside your engine under these conditions. Coolant and oil temperatures increase, even though most gauges are dampened by the factory as to not register these increases, provided they stay within specified limits.

In summary, the average automobile, used for daily transportation and pleasure, stands to benefit the most from a synthetic lubricant. It is also for these reasons, many automobiles are coming off the assembly line with synthetic oil as factory fill.

The most important aspect of oil selection is viscosity. You should closely follow your owners manual and select the viscosity that correlates to your ambient temperatures specific to your geographical location.

Don’t use 5 w 30 just because it recommends this grade on the oil filler cap, as most manufacturers use an oil that will work in the coldest climate they expect the car will be delivered to.

However, Many manufacturers are recommending 5w30 for all climates and suggest that nothing else be used. It is best to abide by these recommendations as the engineers who designed your engine know it best.

For those who plan on owning a vehicle well past its warranty period, I offer this for your consideration.

As an engine wears, clearances increase. This will cause oil pressure to drop as bearing clearances ‘loosen up.’

For these reasons, I would suggest increasing oil viscosity one grade (from 5w30 to 10w30 for example) at about 75,000 miles, providing your ambient temperatures will allow the increase. You will notice a number of ‘high-mileage’ engine oils are appearing on the market now as a number of consumers keep their newer vehicles longer.

Here in California’s Central Valley, summer temperatures often exceed 100°(F) and winter temperatures are rarely below freezing. Based on this geographic setting, a 20w50 engine oil would likely provide adequate lubrication under all climatic conditions, providing it is used in a manner consistent with the manufacturers viscosity recommendation.

In other areas of the country and world, a different viscosity oil would be more suitable based on the ambient temperature of that specific region. The individual owner should compare these factors against what the manufacturer recommends both in terms of viscosity and type of oil (synthetic vs. conventional) used.

As far as an oil recommendation, I believe all currently available conventional and synthetic oils are equal in terms of quality, providing they are changed at sensible intervals. The API Service Grade ‘Doughnut’ on the side of the bottle identifies an oil by a specific service requirement. All oils must pass a series of tests to receive certification. Therefore, the certification is far more important than the actual brand of oil.

Most manufacturers will also recommend a specific certification (like SJ, SH or SL) in their warranty information and these guidelines should also be followed to maintain warranty compliance.

As you can see, the type and grade of oil is often decided for you by the manufacturer, with respect to newer vehicles and their recommendations should be considered the ultimate authority on the vehicle(s) in question.

Inevitably, I am always asked to recommend a specific oil. I honestly cannot offer such advice as most all oils currently available are equal in terms of protection and lubricity, regardless of the oil maker’s claims of superiority.

I am often asked what kind of oil I use in my own vehicles and this question is rather complex. I will do my best to answer it directly and specifically.

In 1984, we switched to Chevron 20w50 Aviation Engine Oil in all of our race cars, including the tow vehicle. I have used this oil ever since in my ‘hot’ street cars and competition engines exclusively.

These are basically large cubic inch, carbureted overhead valve V8 engines and I change the oil at 1,500 to 2,500 mile intervals.

We started using this oil because it has a higher viscosity index (grade for grade) than conventional oils and has greater shear strength. I deemed this necessary for the competition work we were doing at the time.

This is a petroleum based oil that is designed for higher temperature, air-cooled piston engine aircraft operation. It is also ‘ashless,’ meaning when it burns it leaves no residue. These oils are free of metallic detergent additives and instead contain ‘dispersants’ that hold particulate matter in suspension. Many synthetic oils also use a dispersant in their chemical construction.

Additionally, I logged over 100,000 miles in a street-driven 440 Chrysler on this oil. I tore it down for inspection (out of curiosity) and found it amazingly clean inside. Measured wear was negligible and indicative of any high mileage engine. However, the most amazing part of my observation related to the camshaft lobes and lifters.

With very high valve spring pressures (over 280 pounds open) in this application, the camshaft looked absolutely like new. Also, the piston tops and combustion chambers were unusually clean, with nothing more than simple soot deposits that wiped easily away with a shop towel.

Keep in mind this oil would not be a good choice in a late model vehicle, such as the Nissan Xterra, whose tighter clearances and overhead camshaft would not favor such a viscous lubricant, especially at low temperatures. These vehicles will require a different oil altogether.

In my wife’s 1993 Chrysler Mini-Van, I have used Wal Mart Brand (Quaker State) 20w50 since we purchased it. It now has over 200,000 miles on its 3.3 litre V6 and the engine has never been touched. I change the oil and filter every 6,000 to 12,000 miles, which is too long for a conventional oil, but reflective of my busy schedule and general lack of concern for the vehicle in general.

Interestingly enough, I had to remove the oil pan at 115,000 miles to replace a seeping rubber pan gasket that was hardened. When I removed the pan, the engine was remarkably clean inside, with no accumulation of sludge and only minor deposits on the bottom of the piston crowns.

In closing, changing your oil and filter at regular intervals is one of the most important investments you can make in your vehicle. Additionally, the subject of oil & viscosity is second only in controversy to politics and religion.

In general, if you follow the recommendations of the manufacturer, with respect to formulation, ambient temperature and viscosity, you can be assured of doing the very best service possible for your engine.

I hope this information is helpful. Best of luck in your endeavors...Evil Bert

Excellent info Evil Bert (and surprisingly articulate)... I'd give you a good rating but the system is goofy... it won't let me rate most people.

(Originally posted by Kaiser442)>> Oh, and the other unsupported opinion that I've heard from a few friends is that Fram filters are horrible quality. Is it true? Who knows... but thinking about this sort of thing made me start using genuine Nissan filters and parts... you KNOW that those are OK.
>>

I strongly recommend using the Nissan Oil Filter on your Nissan vehicle. Here is what I discovered about Fram Filters.

I have seen a reduction in oil pressure when using a Fram Oil Filter. The reduction was not sufficient enough to be dangerous, but the reduction in oil flow, as evidenced by lower oil pessure, concerned me.

When a Motorcraft FL1A Filter was substituted for the Fram PH8A, the oil pressure came right back up to its previously recorded level.

Here is my opinion on this phenomenon.....

Most people avoid doing maintenance on their vehicles and I beleive Fram has gone to great lengths to create a better filter.

They claim that Fram filters have a higher micron rating than other brands and this would allow a Fram filter to trap more particulate matter.

The byproduct of this extra filtration is a resistance to flow.

On a vehicle that is maintained regularly, residue inside the engine should not be a problem and the additional filtration capacity is probably unnecessary.

Secondly, no one knows more about your Nissan than the engineers who built it and the cost of a genuine Nissa filter is likely to be comparable to most retail suppliers.

Certainly many vehicles operate on Fram filters and have done so for many years. However, I do not think that Fram can compare in terms of quality to the Nissan product.

I hope this information is useful...Evil Bert

That has be without a doubt an XOC record for longest post ever

Good info though.

nah, someone posted the constitution once.

but good info none the less

Yeah but the constitution wasn't original work...
MV

I've posted this link before. But it's been a long time so here it is for all the new members.

Minimopar oil filter study

It's subjective, but some swear by it (I'm in that group) while others scoff and say "It wasn't a quantatative double-blind scientific study so its results are hogwash," (What-ever).

But before anybody puts a Fram oil filter on their "X" I would suggest they at least give this study 5 minutes of their time and decide for themselves what filter to buy.

Hey Evil Bert - about the tolerances you mention.. I've understood that they have been significantly tightened... for example, oil ring clearance on the VG33E is 15 microns...

I'm not sure what kind of tolerances the older engines used to run, but if it's close to what you used to run in the competition engine, maybe it's more worthwhile to run synth now?

-=RB

rb42,

Engine clearances have been reduced in part by advances in material and a desire to improve emissions.

SAE engineers claim reduced clearances allow for the use of much lighter (thinner) viscosity engine oils which are said to have reduced fluid friction.

This reduction is said to improve fuel economy and is why many light oils are marketed as 'Energy Conserving.'

The question remains, how many miles would you have to drive to actually realize a benefit from these oils???

Reduced piston to wall and ring gap clearances are one the way engineers can effectively reduce exhaust emissions.

Keep in mind that domestic engines, such as the ones we used in competition, have much wider ring gaps.

Elevated piston crown temperatures can cause ring end gaps to butt and cause cylinder scoring. This is an extreme case, of course, but it does happen when improperly tuned engines are subjected to the rigors of high rpm useage.

Close ring gaps are more oil efficient, but do not effect the engine's oil requirement.

Since the greatest benefit of synthetic oil is its lubricity under extreme temperatures, ring gaps would have no bearing on oil selection.

I have a 1979 Trans Am WS6 that is one of ony 1,107 ever produced. It is powered by a 6.6 litre OHV Pontiac engine with a 4 speed gearbox and 4 wheel disc brakes.

When building the engine, I bought a set of custom made hypereutectic pistons, to stretch engine displacement to 6.9 litres.

The stock engine required about .004" piston to wall clearance, but the new pistons, made from a new type of material, require only .0025" clearance.

These pistons also have a unique thermal barrier coating that increases their resistence to scuffing and reflect heat into the combustion chamber.

However, the rings still require a relatively wide gap. the top ring is set at .012" the second and oil rings at .010" overall.

The fact is modern metalurgic technology is now available for many parts within the older engines. However, the basic components, such as the block and crankshaft, remain unchanged.

Therefore, clearances can only be closed to a certain extent without creating reliability issues...Evil Bert

Here is the link to Blackstone Labs latest 'oil' newsletter.

News letter

Toy Man

It's funny that study is still floating around. I remember seeing that back in like 1999. I think it has been posted on every auto board since it was created.

I use Mobil 1 filters and Mobil 1 synthetic and have never thought of ever using anything else.

I use Mobil 1 Synth, 5w30 and Mobil 1 oil filters. In my Celica, I used K&N Oil Filters and never had any problems, and I used to let oil changes go WAY too long. I change my X's oil every 3000 miles, whether it needs it or not.

For the record, I went with Valvoline 10w-30 and a Nissan filter. Nissan filter because I got a few for free(but will probably keep using them even when I must pay), Valvoline because it seems to be a high quality oil and I always hear horror stories about this oil or that oil, but only ever good things about Valvoline(for whatever thats worth), 10w-30 because its a good all around choice for my climate(5w-30 seems a little light for the summer, probably ok for winter, which it is now...), and regular rather than syn. just because I feel that for normal uses syn. just doesn't offer benifits to justify its cost, I'm always going to change it at ~3000miles regardless of type, besides I'm weird, I always let it idle for 1-2 minutes before driving off(says 30sec in owners manual), let it get up to temp, make at least one 30 mile trip a week to really let it all get warm and stay warm... stuff like that. For those that said syn isn't that much more than regular only $15 an oil change, what are you paying per oil change? $15 is twice what I spend, and even when I run out of filters, I'll still be spending less (~$12)? What gives? Oh yeah, Evil Bert and I seem to disagree on the values of syn., but it makes for interesting workplace conversation, besides, I never sit idle in a drive-thru, when you want to eat, park, get out, and go in and sit down to eat. Damn people whats so hard about that!
MV

Wow that was a lot of reading! Okay can someone give me good advice on this question?

When do you have to start using synthetic oil? Is this something I can request at the dealer when I buy the X in a couple of weeks? Thanks!

If you're buying a new X and plan on going synthetic here's what I'd do:

First regular oil change after about 1000 miles. Get the original factory oil out.

Again at 3750, regular oil.

At 7k (or 10750), you switch to synthetic. That way, everything has had a chance to seat and break in. You should be good to go after that staying synthetic.