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What is the best Oil Weight to go with

200K views 25 replies 15 participants last post by  03X74008 
#1 ·
Ok so im a college student who is going to school in northern Arizona, Prescott to be exact but i live in Colorado and travel home during the winter break and spring break, and some of the summer. What would be the best compromise with oil weight between the two climates. Prescott where im at most of the time has been know to get below 0 and up to 90+ degrees and its even know to snow a few days out of the year, but when im at home in Colorado its often cold below zero and snows way more and has a high of 80 or so. I believe that i am currently using 10w-30 according to the dealer which is in colorado. Should i stick with that or go with something a little lower for the heat here in AZ?? what's the best oil weight to go with??
 
#3 ·
I would change oil weights/types with the seasons. In the summer, I would run a 10W-30. Years ago, 10W-30 was a bit more thermally stable than it's close cousin, 5W-30. However, it seems most oils will shear a full grade at around 2,000-3,500 miles before gradually thickening up and the difference between 5W-30 and 10W-30 is almost nil. Still, for summer use, I'd choose a 10W-30 over a 5W-30.

In the colder months, I would run a 0W-30 (synthetic) for the cold start-up on bitter mornings.

Don't worry about compatibility as you switch about, all automotive engine oils are compatible and can be mixed. I've been doing this (and reading test samples of used oil) for nearly a decade.

Just be sure to change your oil before 5,000 miles and I don't think you can go wrong with any XW-30.
 
#5 ·
A synthetic 0W-30 would be the best oil, year round. Lots of good synthetics on the market. The best way to determine the OCI and how well it's performing in your engine is to do periodic used oil analyses (UOA). The other advantage of UOAs is they can alert you early to other problems before they become evident.
 
#8 ·
You might not get the right lubrication on start up. whic is the most critical time for proper lubrication. Like I said Nissan recommends 5w30 for a reason. you might as well jus stick with it. 0w30 probably won't hurt, but at the dealership we stick with what is recommended.
 
#9 · (Edited)
I can understand what you're saying, but the more I've read on BITOG, the more the traditional thinking in motor oil recommendations seem to be incorrect. It looks like all oils are too viscous at start up to do an adequate job protecting the engine from the wear that occurs...and the thicker the oil, the worse a job it'll do at this critical period of time.....so it logically follows that a 0W oil will do a better job lubricating a cold engine than a 5W oil will and at operating temp, both oils will be of the same viscosity if they're both 30 weight oils.
Of course, the dealership service dept is going to say use what Nissan recommends....but again, using something just because the manufacturer recommends it doesn't necessarily mean you'll be getting the best protection.
 
#10 ·
You might not get the right lubrication on start up. whic is the most critical time for proper lubrication. Like I said Nissan recommends 5w30 for a reason. you might as well jus stick with it. 0w30 probably won't hurt, but at the dealership we stick with what is recommended.
sigh

A 0w-30 oil is not thinner than a 5w-30 oil.

:D

The weights are an old fashioned way of referring to the oils operating RANGE.

In other words...the oil in the can labeled 5w-30, can pour and provide a protective film on the metal between the ranges of 5 and 30...

...the "30" is not a "thinner 30" because there was a "5" at the other end of the range.

The oil in a can labeled 0w-30 also works between the equivalent 5 - 30 range, it just ALSO works from the equivalent conditions for 5 down to zero as well.

That's all it means.

In the olden days, when they simply mixed some single weight oils together...sure, it was more LIKE THAT (But still not that)...

Nowadays...for the synthetics AND dino juices, they just use a base stock, and add additives to get the ranges they want.

The synthetics need almost NO additives compared to the dino juice, as they do not have the same impurities to compensate for, etc....and can be engineered from scratch for a performance range.

In other words, if the waxes that form when cold are not present to thicken the oil, the oil doesn't need addtives to depress the pout point, to keep it flowing when cold, etc.

So, the synthetic oils can have a much larger operating range, and can both flow better when cold, and stick on better when hot...

...and that range is expressed with the same old fashioned system that we all know and love, with a lower number, a dash, and a higher number.

The low number essentially tells you how it flows when cold, and the higher number tells you how it stays on as a protective film when hot.

:D
 
#13 ·
I have run Mobil 1 5W-30 in the winter and 10W-30 in the summer for all my vehicles the last 15 years.
 
#14 ·
jmoney8659, 1) your engine is under more stress than most at all RPM ranges. And 2) a supercharged engine is more likely to dilute the oil with fuel.

Both of these tend to increase wear (gasoline is a poor lubricant and a powerful solvent)

Given you are in Tennessee, I would use a 10W-30 conventional or nearly any XW-30 synthetic (see below if you pick Mobil 1).

'rat, look at the pour points for both Mobil 1 5W-30 and 10W-30. You could use their 10W-30 year 'round with no problems, I'm sure. So, if this makes it easier for you from an oil stockpile point of view, then that's what I'd do.

One thing about Mobil 1, though, it starts off a touch thin in each grade. I like to think of their 5W-30 as almost a 5W-25. There's nothing wrong with this as most engines are perfectly happy (even happier) using lighter viscosity oils. But if you have a fuel dilution problem (worn rings, many cold starts and the engine tends to run rich), figure that the Mobil 1 will effectively thin out quickly. Then, most Mobil 1 grades have a light metallic additive package, so wear protection may not be exactly great once this stuff has some miles and thinning on it.

I don't say this to alarm anyone. Mobil 1, especially their EP grades, is pretty good stuff. But I caution people who are using this stuff not to go to far before draining just because they think they are using the 'best stuff available' and they can get away with 8,000-10,000+ mile intervals. There is a reason they came out with the "EP" formulas ... it's Mobil 1's traditionally weak additive package.

Pennzoil Platinum is better for vehicles that tend to have fuel dilution issues (because of its additive package). This is a pretty common condition if you do a lot of cold starts and short trips. I am posting a UOA on BITOG tonight using this oil. The OLM on my car told me it was about time for a change (almost down to 20%) but the oil held up VERY well.
 
#19 · (Edited)
As a chemist please allow me to add my 2 cents fellas:

In general 10w-30 is a much more stable oil than 5w-30
(assuming its otherwise a similar formulation)

Reason is less viscosity index improvers are used/needed to bridge the gap form the Xw cold run viscosity to the warm running 30 weight.

What IS a multiviscosity oil?

A 5w-30 is a 5w oil thats been improved so it only thins out as MUCH AS A #) WEIGHT WOULD when it gets warmer.

Thats whats called multivis
This is easier to accomplish over smaller spreads like 10w-30 has less VIIs
Why does this matter?

VIIs dont add anytthing to lubrication itself , so the less you have the mor eoil you have in a given quart formualtion.
This is good

Also VIIs decompose into varnish
This is bad

The thing about syntheic oils is that they need much less VIIs to make multivis bahviour happen.

This makes possible the excellent Mobil1 ow-40 and Valvoline Syn 5w-40 .
So you cna get more multivis bavhious w/o overloading the formulaiton w/ VIIs

Conversely a syn 5w-30 has very little VIIs and many synthetic 10w-30s have no VIIs at all.

I used ot race lot and use a fill of Mobil 1 0w-40 all year around, or redline 5w-40, which are both protect great against viscosity break down AND cold startup.

The VQ series of engines does not have the hotspots of some some other engines but even here I prefer to run 10w-30 year round in milder climates.
10w-40 maybe Valvoline Durablend in hot climates, or Castrol Syntec 0w-30 in cold climates.

(The VQ37 in the Z and G has hotspots and runs hot, thats why they only want to see a 5w-30 in it if its a very high end ester oil.. w/o high end chemistry you cant make a 5w-30 work well in those hot engines. The option to just go with a Xw-40 weight Nissan cant take because CAFE gets calculated based on factory fill, and this is whats responsible for the manual saying 5w-30 only. )

Just FYI in other countries Nissan still recommends changing the viscosity w/ the seasons like it used to do here.
0:)
 
#21 ·
Thanks for the info! I live in the Caribbean so most of the year is super-hot and humid, lots of traffic 33c on day 25c on night, 200 miles a week with almost none highway driving. The longest trip you can do here is 3 hours from point to point.

My engine is 150k, it uses gasoline and LPG (http://lovato-autogas.com.au/) Do I have to stick to 5w30 or should use something different?
Do you not have to stick with 5w-30. In your situation it is likely sub-optimal.

Go with a 10w-40.

If you are on a budget, the Kendall, Castrol GTX and Valvoline Durablend in 10w-40 are all excellent choices.
If not on a budget: , Mobil1 0w-40 or 15-50, Valvoline Synpower 5w-40 and the best of course Redline in either 5w-40 or 10w-40
 
#22 · (Edited)
jmoney8659, 1) your engine is under more stress than most at all RPM ranges. And 2) a supercharged engine is more likely to dilute the oil with fuel.

Both of these tend to increase wear (gasoline is a poor lubricant and a powerful solvent)

Given you are in Tennessee, I would use a 10W-30 conventional or nearly any XW-30 synthetic (see below if you pick Mobil 1).

'rat, look at the pour points for both Mobil 1 5W-30 and 10W-30. You could use their 10W-30 year 'round with no problems, I'm sure. So, if this makes it easier for you from an oil stockpile point of view, then that's what I'd do.

One thing about Mobil 1, though, it starts off a touch thin in each grade. I like to think of their 5W-30 as almost a 5W-25. There's nothing wrong with this as most engines are perfectly happy (even happier) using lighter viscosity oils. But if you have a fuel dilution problem (worn rings, many cold starts and the engine tends to run rich), figure that the Mobil 1 will effectively thin out quickly. Then, most Mobil 1 grades have a light metallic additive package, so wear protection may not be exactly great once this stuff has some miles and thinning on it.

I don't say this to alarm anyone. Mobil 1, especially their EP grades, is pretty good stuff. But I caution people who are using this stuff not to go to far before draining just because they think they are using the 'best stuff available' and they can get away with 8,000-10,000+ mile intervals. There is a reason they came out with the "EP" formulas ... it's Mobil 1's traditionally weak additive package.

Pennzoil Platinum is better for vehicles that tend to have fuel dilution issues (because of its additive package). This is a pretty common condition if you do a lot of cold starts and short trips. I am posting a UOA on BITOG tonight using this oil. The OLM on my car told me it was about time for a change (almost down to 20%) but the oil held up VERY well.
Good post.

The Mobil1 10w30 is only 30 weight I like in Mobil1 . Otherwise I have used MObil 1 0w-40 and 15w-50 in my supercharged VQs
 
#23 ·
No reason to stick with the recommended 5w-30.
CAFE has a lot to do with this recommendation.

10w-40 in Arizona.
When you look at old (or some international) nissan manuals for VQ engines they generally recommend 10w-40 in summer for NA engines.

Since u are a college student stick w/ Kendall 10w-40 or Castol GTX 10w-40 or the Shell non syn 10w-40m (walmart, good stuff)

No need to spring for synthetic in these engines.
 
#24 ·
The en?ine sounds very noisy, even new one at start up. An automobile write up in a car magazine referred to it as an "industrial sounding motor". If you are in a warm or hot climate, run 20w-50. It will quiet the motor, protect it in hot weather, and if you drive an xterra do not expect gas mileage regardless of oil viscosity. Oh! Did I not mention noisy timing chains and guides at higher mileage becoming an issue.
 
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