[FNFAL308]

First I'll apologize now for asking a Q surely asked and answered a 1000 times before..

That being said I have actually "tried" to gather info on my own so as to make a good, educated decision on what oil to use in my RODEO..
However I've just not found enough specific info to make a determination I'm 100% happy with...

FIRST, I tried my Owners Manual only to find those two specific pages MISSING....

I've tried the SEARCH function here and even after a number of diff attempts (and words, like OIL, ENG OIL, RODEO OIL, OIL CHANGES, ETC, ETC) I ended up with nothing?

I went to BOB THE OIL GUY's forums and can't even find a "SEARCH" function (although it may be for registered users only of which I am waiting acceptance)? Did find some good info though in the OIL UNIVERSITY and have at least some thoughts from that..

Assuming the FIRST number determines how oil flows when it's at ambient temp, it "seems" to me that a 0-XX, or 5-XX would be best?

That being said would CASTROL SYNTEC, or the SYNTEC BLEND 5-30 be a good choice? Maybe a 5-40 is best?

Would reg old Castrol, or another brand oil give me good results? While I've used CASTROL for many years I'm not against using something else since apparently my choice of 20-50 WT oil all these years has been wrong anyway..

I'm changing oil in all three vehicles next weekend so I'm hoping to have enough info by then to make my "educated" decision..
Vehicles will be a 95.5 RODEO W/3.2 SOHC, a 2001 RODEO W/3.2 DOHC, and my Wife's 2001 NISSAN X-TERRA also with a 3.2 (IIRC?) V-6..

TIA for any/all assistance you all may care to share..

 

[Apeiron]

Stolen from Wikipedia:

Single-grade
A single-grade engine oil, as defined by SAE J300, cannot use a polymeric Viscosity Index Improver (also referred to as Viscosity Modifier) additive. SAE J300 has established eleven viscosity grades, of which six are considered Winter-grades and given a W designation. The 11 viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. These numbers are often referred to as the 'weight' of a motor oil; and single-grade motor oils are often called "straight-weight" oils.

For single winter grade oils, the dynamic viscosity is measured at different cold temperatures, specified in J300 depending on the viscosity grade, in units of mPa·s or the equivalent older non-SI units, centipoise (abbreviated cP), using two different test methods. They are the Cold Cranking Simulator (ASTMD5293) and the Mini-Rotary Viscometer (ASTM D4684). Based on the coldest temperature the oil passes at, that oil is graded as SAE viscosity grade 0W, 5W, 10W, 15W, 20W, or 25W. The lower the viscosity grade, the lower the temperature the oil can pass. For example, if an oil passes at the specifications for 10W and 5W, but fails for 0W, then that oil must be labeled as an SAE 5W. That oil cannot be labeled as either 0W or 10W.

For single non-winter grade oils, the kinematic viscosity is measured at a temperature of 100 °C (212 °F) in units of mm²/s or the equivalent older non-SI units,Stokes (centistokes]] (abbreviated cSt). Based on the range of viscosity the oil falls in at that temperature, the oil is graded as SAE viscosity grade 20, 30, 40, 50, or 60. In addition, for SAE grades 20, 30, and 40, a minimum viscosity measured at 150 °C (302 °F) and at a high-shear rate is also required. The higher the viscosity, the higher the SAE viscosity grade is.

For some applications, such as when the temperature ranges in use are not very wide, single-grade motor oil is satisfactory; for example, lawn mower engines, industrial applications, and vintage or classic cars.

Multi-grade
The temperature range the oil is exposed to in most vehicles can be wide, ranging from cold temperatures in the winter before the vehicle is started up, to hot operating temperatures when the vehicle is fully warmed up in hot summer weather. A specific oil will have high viscosity when cold and a lower viscosity at the engine's operating temperature. The difference in viscosities for most single-grade oil is too large between the extremes of temperature. To bring the difference in viscosities closer together, special polymer additives called viscosity index improvers, or VIIs are added to the oil. These additives are used to make the oil a multi-grade motor oil, though it is possible to have a multi-grade oil without the use of VIIs. The idea is to cause the multi-grade oil to have the viscosity of the base grade when cold and the viscosity of the second grade when hot. This enables one type of oil to be generally used all year. In fact, when multi-grades were initially developed, they were frequently described as all-season oil. The viscosity of a multi-grade oil still varies logarithmically with temperature, but the slope representing the change is lessened.[8] This slope representing the change with temperature depends on the nature and amount of the additives to the base oil.

The SAE designation for multi-grade oils includes two viscosity grades; for example, 10W-30 designates a common multi-grade oil. The two numbers used are individually defined by SAE J300 for single-grade oils. Therefore, an oil labeled as 10W-30 must pass the SAE J300 viscosity grade requirement for both 10W and 30, and all limitations placed on the viscosity grades (for example, a 10W-30 oil must fail the J300 requirements at 5W). Also, if an oil does not contain any VIIs, and can pass as a multi-grade, that oil can be labelled with either of the two SAE viscosity grades. For example, a very simple multi-grade oil that can be easily made with modern base oils without any VII is a 20W-20. This oil can be labeled as 20W-20, 20W, or 20. Note, if any VIIs are used however, then that oil cannot be labeled as a single grade.

The real-world ability of an oil to crank or pump when cold is potentially diminished soon after it is put into service. The motor oil grade and viscosity to be used in a given vehicle is specified by the manufacturer of the vehicle (although some modern European cars now have no viscosity requirement), but can vary from country to country when climatic or fuel efficiency constraints come into play.

But anyway, use any oil of the manufacturer's recommended grade, and just change it on schedule.

 

[vanduker]

For the Isuzus I think the top choice of people here would be the Rotella T 5w-40. Is a synthetic and reasonably priced in gallons at Wal Mart.

There are a lot of good oils out there, Syntec, normal Castrol, Mobil1, Valvoline and so on - all viable - but I think overall you will find people using the Rotella.

I've used the Rotella 15w-40 (is non synthetic) in some of mine at least when it is warm outside and it worked great as well.

On the X TERRA just put the old Isuzu oil in there. LOL just kidding. I'd look in the manual for the suggested weight.

 

[Ramblin Fever]

In your neck of woods, any good 10w-30 would be just fine for all 3

I use Maxlife 10w-30 in my 97 3.2L as well as my 3.8L caravan

0w-30 is superb for those that live in SUPER cold climates and not really necessary, IMHO for the rodeo's for sure.

Yes, you're correct when you stated 0w and 5w are better for cold starting in the winter time; in summer time temps, or any temp above 40f, the lower number doesn't really make that big of a difference.

I personally don't like to use oils with a huge number difference, i.e. 0w-30 or 0w-40, the farther between those two numbers, the more volitales are in the oil and the more deposits it can actually leave behind or break down faster.

 

[FNFAL308]

Thanks for the replies so far..

Ramblin Fever I am now registered on Bobs site and saw a few of your posts..

Would one of you guy's be able to tell me what Isuzu's Oil recommendation is on the 01 3.2 DOHC? As Noted above those pages are missing from my Owners Manual..

Thanx, MIKE

 

[vanduker]

PM Me an email address and I will send you the page from the shop manual.

 

[FNFAL308]

Got my Rodeo and the Wife's X-Terra done this afternoon..
Decided on CASTROL 10-30 for the Rodeo's and 5-30 for the X-terra (per manual recommendation)..

Changes were easy as pie although I did choose to remove the skid plates for easier cleanup and filter access...

The Local ADVANCE AUTO has an Oil change special running right now..
5 Qts of CATROL plus a Purolator Filter for $18.00.. Add another $2.00 and upgrade to the Purolator-1 filter which is what I did.

Thanks to Vanduker for helping me out with the oil specs for my Rodeo.. ccasion5: