Now that it is getting colder outside I'm preparing to change oil in my truck. I live in Illinois just East of St. Louis. Occasionally the temps will fall below 10*F which is out of the 15w-40 range according to the chart. I'm curious what some of you guys do regarding oil changes and viscosity? Do you change oil in the fall to 10w-30 and then again in the spring back to 15w-40? I know I can buy 5w-40 but all I've seen is a full synthetic. I only put about 6k on my personal truck in a year, so when I had my gasser I would change oil at the 3k mark. I've only got about 2500 miles on this truck since the last oil change. I hate to change oil unnecessarily but again I don't want to damage the engine. I guess if I went to the 5w-40 full synthetic I could get away with changing oil once a year, but I am leery of doing it. I've never used a full synthetic in my vehicles and changing oil only once a year makes me a little nervous. What are your thoughts??

I've been using 15w-40 all the way down to -20*F no issues here... I just allow it to warm up to 100*F worth of coolant before driving...

I just canned amsoil and went to valvoline premium blue 15/40 non synthetic, starts up faster than amsoil, have tested it down to 20F so far, works flawlessly. I live in sedalia, MO and doubt it will get to -20F here. I have seen down to maybe -10F. In any case you should have it plugged in if it is in the negatives, no matter what oil you run.

ive run 15-40 in mine since it was new in temps down to 0, dont see that very often it depends on where i am working. let it warm up just as MM says before driving. pugging it in helps also. mine has never refused sart or been hard to start even down to 0 pugged in or not.

if it has been sitting ..change it..i have always heared if you go to syn.that you are not suppose to go back to conventional..dunno..maybe a myth..so i dont do it/or use syn. in my rig!!

I run 15W-40 year round without any issues. If you are concerned about extreme cold weather cold starts, be sure to plug in the block heater to your truck at least 3 hours before you attempt a start and use an oil pan heater of some sort. This should keep the oil at an acceptable viscosity for cold starts. http://compare.ebay.com/like/200534230808?ltyp=AllFixedPriceItemTypes&_dmd=Gallery&var=sbar&rvr_id=179592568552&crlp=1_263602_304692&UA=WVI7&GUID=db2fa7cb1290a02652f215c2ff0c4602&itemid=200534230808&ff4=263602_304692 http://compare.ebay.com/like/230554772415?ltyp=AllFixedPriceItemTypes&var=sbar&rvr_id=179618500413&crlp=1_263602_304662&UA=WVI7&GUID=db2fa7cb1290a02652f215c2ff0c4602&itemid=230554772415&ff4=263602_304662 http://cgi.ebay.com/Kats-Handi-Heat-Magnetic-Heater-300-W-1160_W0QQitemZ280599138961QQcategoryZ20613QQcmdZViewItem http://cgi.ebay.com/ebaymotors/Kats-Magnetic-Heater-Part-1160-Magnum_W0QQcmdZViewItemQQcategoryZ6763QQitemZ180594627132

I just canned amsoil and went to valvoline premium blue 15/40 non synthetic, starts up faster than amsoil, have tested it down to 20F so far, works flawlessly. I live in sedalia, MO and doubt it will get to -20F here. I have seen down to maybe -10F. In any case you should have it plugged in if it is in the negatives, no matter what oil you run.

Looking at the cold pour temperatures of AMSOIL versus a Group II conventional like Val Prem Blue, what you say makes no sense scientifically. In a cold diesel engine in the winter, not plugged in, AMSOIL will flow much easier than any Group II oil on the market. When I'm at work up here in northern Minnesota, temps can get -20 during the day and I have nowhere to plug in for 10 hours. I'll stick with the Group IV AMSOIL. -Chuck

Looking at the cold pour temperatures of AMSOIL versus a Group II conventional like Val Prem Blue, what you say makes no sense scientifically. In a cold diesel engine in the winter, not plugged in, AMSOIL will flow much easier than any Group II oil on the market. When I'm at work up here in northern Minnesota, temps can get -20 during the day and I have nowhere to plug in for 10 hours. I'll stick with the Group IV AMSOIL. -Chuck

So what does that have to do with it not getting to -20F here? I realize from -20 to -44, you need synthetic, but if it is over -20, then what. I have been speculating that because the amsoil "flows so well" that when you let the engine sit for a long time, a lot of oil goes to the pan. Now the other oil being thicker will surely not go to the pan as easily. So when you start it, the engine has no oil pressure, but the engine with the thick conventional oil has more oil up on there since it never drained off, therefore allowing it to spin easier. I can't prove it, but it has been starting up faster than amsoil ever did in the cold, consistently.

So what does that have to do with it not getting to -20F here? I realize from -20 to -44, you need synthetic, but if it is over -20, then what. I have been speculating that because the amsoil "flows so well" that when you let the engine sit for a long time, a lot of oil goes to the pan. Now the other oil being thicker will surely not go to the pan as easily. So when you start it, the engine has no oil pressure, but the engine with the thick conventional oil has more oil up on there since it never drained off, therefore allowing it to spin easier. I can't prove it, but it has been starting up faster than amsoil ever did in the cold, consistently.

AMSOIL not only keeps your engine much cleaner internally than a conventional Group II oil, it is much more thermally stable at high temperatures. It doesn't "cook off" or volatilize nearly as fast as a conventional oil. Remember, no matter what your ambient air temperature is, your turbo is constantly exposing your oil to 600 to 1400 degree Fahrenheit temperatures. Thermal stability is important for all turbo diesels, regardless of climate.

-Chuck

--- Update to the previous post...

Base Oil Categories

The American Petroleum Institute (API) developed a classification system for base oils that focuses on the paraffin and sulfur content and degree of saturation of the oil. The saturate level indicates the level of molecules completely saturated with hydrogen bonds, leaving them inherently un-reactive. There are five groups in the classification system, ranging from Group I – Group V.

Base Oil Characteristics by Group

Group I Characteristics

Group I base oils are the least refined of all the groups. They are usually a mix of different hydrocarbon chains with little uniformity. While some automotive oils use these stocks, they are generally used in less- demanding applications.

Group II Characteristics

Group II base oils are common in mineral-based motor oils. They have fair to good performance in the areas of volatility, oxidation stability, wear prevention and flash/fire points. They have only fair performance in areas such as pour point and cold-crank viscosity.

Group III Characteristics

Group III base oils feature reconstructed molecules that offer improved performance in a wide range of areas, as well as good molecular uniformity and stability. By definition, they are a synthesized material and can be used in the production of synthetic and semi-synthetic lubricants.

Group IV Characteristics (AMSOIL)

Group IV base oils are made from polyalphaolefins (PAO), which are chemically engineered synthesized base stocks. PAOs offer excellent stability, molecular uniformity and improved performance.

Group V Characteristics

Group V base oils are also chemically engineered stocks that do not fall into any of the categories previously mentioned. Typical examples of Group V stocks are Esters, polyglycols and silicone. As with Group IV stocks, Group V stocks tend to offer performance advantages over Groups I – III. An example of a mineral-based Group V exception would be a white oil.

Defining Mineral Oil Properties

Mineral oils are generally classified as paraffin and naphthenic. The difference between paraffin stocks and naphthenic stocks is one of molecular composition, resulting in inherent solvent differences between the two types of stock.

Paraffinic Stock

Paraffinic oils are characterized by straight chains of hydrocarbons where the hydrogen and carbon atoms are connected in a long linear composition, similar to a chain.

The wax matter within the paraffin stock results in these elements turning to solids at low temperatures; therefore, untreated paraffin stocks do not have good cold-temperature performance and consequently, the pour point of paraffin stocks is higher. In order for a paraffin stock to flow at low temperatures, the heaviest waxes must be removed and usually pour-point depressants are necessary.

Paraffinic stocks display good high-temperature performance with high oxidation stability and high flash/fire points. Paraffinic stocks also have a high viscosity index (VI), meaning that they exhibit high viscosity stability over a range of temperatures.

Naphthenic Stock

Naphthenic oil stocks are much like paraffin stocks in that they contain only hydrocarbons. However, naphthenic stocks differ, and are characterized by a high amount of ring hydrocarbons, where the hydrogen and carbon atoms are linked in a circular pattern. Conventionally, when the paraffin carbon content of oil is less than 55 - 60 percent, the oil is labeled as naphthenic.

Naphthenic crudes contain very little to no wax and therefore will remain liquid at low temperatures; however, they will thin considerably when heated. Naphthenic stocks generally have a low viscosity index. These stocks have higher densities than paraffin stocks, and they have greater solvency abilities than their paraffin counterparts. Because naphthenic stocks contain little wax, they display lower pour points than paraffin stocks. These stocks are also volatile and have a lower ash point.

Because naphthenic crudes contain degradation products that are soluble in oils, they present fewer problems with the formation of sludge and deposits. Due to the performance characteristics of naphthenic oils, they are generally used in applications where low pour points are required and the application temperature range is narrow.

Defining Synthetics

A true definition for the term synthetic oil has been difficult to reach, although it has generally been accepted that the term represents those lubricants that have been specifically manufactured for a high level of performance. In 1999, the National Advertising Division (NAD) ruled that Group III base oils with very high viscosity indices can be called synthetic oils.

The construction of a synthetic base stock will vary depending on the particular stock. While mineral stocks are derived through a distillation process, synthesized stocks are derived from a chemical reaction process. Synthetic lubricants are engineered for a specific molecular composition; they undergo a specific reaction process to create a base fluid with a tailored and uniform molecular structure. This allows chemists to develop lubricants with specific and predictable properties.

While an average mineral oil stock may possess a moderate amount of semi-beneficial molecular compounds, synthetic stocks, by design, can be composed completely of beneficial molecular compounds. Because of this, synthetic stocks are able to extend the service life of both oil and equipment, and they also have a wider range of acceptable temperature margins than conventional stocks.

Oftentimes people misunderstand the term "synthetic lubricant", believing it refers to one type of stock, when it in fact represents a number of oil stocks. While it can be generalized that all synthetic lubricants have superior performance capabilities over mineral oils, the variations in characteristics can be significant. One synthetic stock can be excellent for the production of motor oils and drivetrain fluids, while others will be totally unacceptable for such applications.

The most common synthetic base stocks used in the transportation industry are PAOs, esters, and Group III oils. Keep in mind that within each family name, additional sub-groups may exist. For example, esters can be further divided into sub-categories of esters with varying properties.

Synthetic Hydrocarbons

Synthetic hydrocarbons are the fastest-growing synthetic lubricant base stock. Synthetic hydrocarbons are fluids that are formulated to specifically meet critical requirements and provide superior performance. These fluids often are made from a single type of molecule, usually of restricted molecular range. Such tailored fluids provide increased performance characteristics over petroleum stocks.

Synthetic hydrocarbon base stocks can be used in combination to provide characteristics such as solvency, temperature performance, surface strength and volatility qualities.

Polyalphaolefins (PAOs) Group IV

Of all the synthetic base materials, PAOs are likely the closest relative to mineral oil stocks. Both types of oil stocks are comprised of similar hydrocarbon molecules; however, PAO stocks (Group IV) consist of a single molecular structure, whereas mineral oil (Group III) contains a broad range of structures.

PAOs are commonly manufactured by reacting ethylene gas with a metallic catalyst. The major advantage of PAOs is their ability to function over a broader temperature range than their mineral-based counterparts. PAOs also provide improved stability, which helps to reduce engine deposits. Correctly formulated PAOs have the ability to hold large quantities of contaminants in suspension, further reducing deposits.

Group III Oils

Group III oils undergo the most stringent level of conventional refining techniques for petroleum oils; most of the waxes and impurities naturally occurring in the oil are removed. The high level of refining gives Group III oils a high level of performance. Since the ruling of the National Advertising Division (NAD) of 1999, Group III oils can be legally called synthetic oils. The decision was based on the amount of refining the oil is subjected to.

AMSOIL Advantage

Thermal Stability

AMSOIL synthetic base oils have better thermal stability than mineral oils. Thermal stability permits the oils to be used longer, even as speeds and temperatures increase. It also allows oils to retain their viscosities at low temperatures. Lower-viscosity oil provides better cold-weather operation, allowing the oil to be quickly circulated at cold-temperature start-ups and providing engine components with the proper lubrication to keep them protected.

High Viscosity Index

AMSOIL lubricants are formulated to have naturally high viscosity indices, so the need for viscosity index improvers is reduced. The VI improvers used in AMSOIL lubricants are temperature specific, meaning they are activated only when certain temperature requirements are met. In most cases, VI improvers help maintain thickness at higher temperatures while having minimal effect at low temperatures. By using viscosity improvers with a high shear-stability index, AMSOIL is able to achieve optimal cold-weather performance with virtually no loss to shear-stability performance.

AMSOIL lubricants resist thinning at high temperatures (high VI) and can suppress the generation of additional friction and heat generated by components in contact due to a thinning lubricant.

Stable Viscosity

AMSOIL synthetic lubricants maintain viscosity under extreme temperature fluctuations and shearing forces; they meet requirements set forth for multi-viscosity oils requiring a minimum oil viscosity. Whereas some conventional mineral oils degrade when exposed to high temperatures and high forces, AMSOIL lubricants offer superior wear protection in extreme temperatures.

AMSOIL synthetic lubricants are inherently better at maintaining viscosity over a wide range of temperature (high VI), and, coupled with shear-stable VI improvers, they maintain viscosity characteristics better at high temperatures and for longer durations than conventional oils.

High Hydrolytic Stability

AMSOIL lubricating fluids display high hydrolytic stability. Under the most demanding conditions, they form very little acid and insoluble contaminants. This helps to reduce acid forma␣on, foaming and contaminant forma␣on, ensuring the lubricant is acceptable for long-term use.

Less Volatility

AMSOIL synthetic lubricants are engineered to have uniform molecular shapes and weights. The advantage to this homogeneous composition is that there are less ‘light fractions’ that are susceptible to evaporation. AMSOIL synthetic lubricants are more stable than conventional motor oils and resist burn-off.

High Flash and Fire Points

AMSOIL synthetic lubricants display high flash and fire points, meaning they are highly resistant to breakdown at normal operating temperatures. They offer more protection than conventional oils because they resist oxidation and thermal breakdown, retaining their pumpability and heat- transfer abilities.

Saturated Molecular Structure

AMSOIL synthetic lubricants are formulated with base oils that have a saturated molecular structure, meaning oxygen is prevented from attaching. This provides inherent heat and oxidation stability over conventional oils that are unsaturated. Because AMSOIL oils do not contain contaminants like conventional mineral oils, their base composition does not accelerate oxidation.

AMSOIL products contain oxidation inhibitors that are far better than conventional oils. Oxidation inhibitors are sacrificial in nature, meaning they deplete, or are used up over time. Since AMSOIL base oils have better oxidation stability on their own, oxidation inhibitors in AMSOIL oils last longer because they are not depleted as rapidly. AMSOIL uses a combination of oxidation inhibitor systems for different temperatures and application needs.

Advanced Additive Packages

AMSOIL exceeds industry specifications by incorporating precise amounts of the best additives into lubricants for superior performance benefits. For example, AMSOIL uses organic compounds called metal passivators to protect yellow metals like copper and brass from corrosion.

AMSOIL uses heat-resistant additives to prevent lubricant breakdown in order to maximize the oil’s service life. This approach of perfectly balancing protection and performance ensures that AMSOIL lubricants fully guard equipment during extreme-pressure operations.

Soot Control

AMSOIL lubricants effectively handle soot and other contaminants. The saturated composition of AMSOIL synthetic lubricants help keep soot in suspension, which significantly minimizes large clusters that deposit on components and increase wear rates. The dispersant package in AMSOIL motor oils coupled with their overall composition provides enhanced soot control over conventional lubricants.

High TBN

Because AMSOIL lubricants contain consistently high TBNs (Total Base Number), they neutralize acidic contaminants formed during the combustion process and keep these contaminants in suspension to prevent corrosion.

AMSOIL lubricants use detergent and dispersant additives to significantly reduce sludge and carbon deposit formation better than conventional oils.

Dont mean to hijack a thread....but not that long ago i remember reading a thread on here or CF from a guy that had been running Syn. Oil (Amsoil) sence New and had replaced his Cam with a Aftermarket cam just for performance reasons and was commenting on how much wear was on that OE cam.. I have searched back thru the old threads and have not came across it...Maybe someone will chime in that seen it also.. Richie

Dont mean to hijack a thread....but not that long ago i remember reading a thread on here or CF from a guy that had been running Syn. Oil (Amsoil) sence New and had replaced his Cam with a Aftermarket cam just for performance reasons and was commenting on how much wear was on that OE cam.. I have searched back thru the old threads and have not came across it...Maybe someone will chime in that seen it also.. Richie

From my experience with cam wear and or failures, it is not the oil itself that damages cams it is improper adjustments of valves and contaminants namely soot in the oil that drastically shortens the life span of all the moving parts. If he had big injectors in it and did not run a bypass filter I would venture to guess that soot levels in the oil got pretty high.

Dont mean to hijack a thread....but not that long ago i remember reading a thread on here or CF from a guy that had been running Syn. Oil (Amsoil) sence New and had replaced his Cam with a Aftermarket cam just for performance reasons and was commenting on how much wear was on that OE cam.. I have searched back thru the old threads and have not came across it...Maybe someone will chime in that seen it also..

you speak of our very own AH64ID. here is his threads...first one is when he did his cam swap. http://forum.mopar1973man.com/threads/1627-3rd-Gen-Cam-upgrade?highlight= this is where he says that his last UOA was good for continued use, but he had more wear on his cam than he would have liked to see. http://forum.mopar1973man.com/threads/2225-When-do-you-change-YOUR-oil?highlight=cam+wear Wild&Free is right. soot is the killer. your lube oil suspends the soot and contaminants in the oil. when you change your oil, the contaminants come out as well. the oil can only hold so much. when you reach that point, you start forming sludge. extended oil intervals are a balancing act of "holding to much, or can hold some more". most by-pass filters cannot remove soot as it is too small.