wmanimal

Just wondering what the "general" consensus is on getting oil changes when using synthetic oil. My dealer recommends every 5,000 but that sounds a little excessive. Thanks!!!

lightonthehill

I wouldn't change from dino to synthetic before at least 10,000 miles on the odo. I actually prefer 20K before switching to synthetic.

Synthetic oil lasts longer than dino oil. It probably would lubricate fine for 50K miles or more. Dino might last 25K miles.

But the same pollutants will be deposited into whatever oil you are using. So when we change oil, it isn't because the oil has lost its ability to lubricate; its because we need to get the dirt, crud, particles, pollutants, etc, that are in the oil out of the engine.

That is why your dealer might suggest 5,000 miles between synthetic oil changes and 3,750 between dino oil changes.

You need to 'play it safe' while under warranty. You might have to follow the dealer's advice.

If it were not for the warranty implications, with normal driving, I would probably go around 4,500 to 5,000 between dino oil changes and 6,000 to 7,500 between synthetic oil changes.

MDS

Lightonthehill, as usual you make great contributions to the org. You raised a point regarding oil changes that I never fully understood. I’d appreciate your, or anyone’s input. It regards the real-life benefit of synthetic oil. You wrote:

That always made sense to me. For example, if I fill my engine with synthetic oil, I know that because of its superior molecular structure, its viscosity won’t break down for at least 15,000 miles. Now let’s assume I pour a cup of fine sand into the engine. Even though the oil is fresh, that sand will still circulate through the engine and wear down the internal components. Although the synthetic oil is fresh and viscous, I would still need to change it immediately to avoid internal damage caused by the abrasive sand particles.

Does that logic make sense? If it does, it almost creates an argument against the benefits of synthetic oil. Now wait! I’m not criticizing synthetic oil. I know it is better. I just question if we keep the oil in the engine long enough to take advantage of its superior molecular structure, longer life span, and higher price.

As I believe Lightonthehill stated, we change our oil because it becomes dirty and abrasive, not because of viscosity breakdown. If dino oil breaks down at 8,000 miles, and synthetic oil breaks down at 16,000 miles, what difference does it make if both oils need to be changed at 4,000 miles because of contamination? At 4,000 miles, neither oil has broken down and still provides great lubrication. But, both oils are equally dirty and circulate the same abrasive particles through the engine. Why pay the extra money for long-life synthetic oil if it needs to come out at essentially the same time as dino oil, which hasn’t broken down yet?

I know millions of knowledgable people swear by synthetic oil. What am I missing? Thanks.

dcastine

I use Synthetic because it doesn't thin in the heat of the engine, and thicken in the cold temps of the Winter... for what it's worth, I had a 1998 BMW 540/6spd that I ran from 20,000 miles to 245,000 miles. I would've kept driving it but it was involved in a rear-end collision, I decided to keep the car and part it out the car because of the mods. I then took the engine apart. It looked good as new, I mean REALLY REALLY clean, very impressive...

I continue to run Mobil-1 5w-30 and change it at 5,000 mile intervals in my 2006 Hemi Quadcab RAM pickup, which incidentally I'm trading in for an 07 SE tomorrow!

I have some older MoPARs that I run dino in, they never see heat or winter, and I'm afraid of the leaks I hear about when changing to synth in the older engines...

Take care,
Dave C
www.VintageCarsOnline.com

MDS

Congrates on the 07 Max! I can tell you like your cars, particualry the 540/6 spd. That big Hemi is a nice torque monster.

Permit me to keep asking questions. Based on my understanding, the "5w/30" describes the heat characteristics of the oil. To the best of my knowledge, a 5w/30 dino oil thins or thickens exactly the same as a 5w/30 synthetic oil. In this respect, there is no difference between the two and no advantage for the synthetic.

Not to be a pain the backside, but you buy expensive synthetic oil that can last 15,000 miles, but change it at 5000 miles. You obviously have your reasons. May I ask what they are? Was it just for the heat? Thanks.

haasem

I use Amsoil. I dorve my 1999 maxima over 218,000 using Amsoil. I change the oil once a year and the filter every six months.

Simply stated synthetic is better oil. Synthetic at 20,000 miles is better than conventional oil at 2,000 miles.

jsuggs

I have often question about using DINO as opposed SYN oil. I have used Mobile1 for years. And have had many new cars. The one thing that I noticed with the 1st oil change to Mobile1 was how much quieter the engine became . In every car !! I still change as per the manual. I could go more miles but I do not. And I do get a warm and fuzy feeling using Mobile1 over Dino. But in my case it just might be a " State Of Mind " ..

If I was a high performance nut I would ALWAYS use top shelf oil ... period and change it frequently. If you are only going to keep a car 3-4 years I dont think it is going to make any difference in what type of oil you use unless you want the next owner to bennefit !!

Bottom line ........ If you are going to keep the car a LONG time use top shelf oil... Otherwise us Dino top brand !!

John ..

haasem

High quality synthetics have a longer service life, better thermal and oxidation stability, soot handling capability and viscosity retention; superior cold flow properties; improved fuel economy benefits and lower deposit formation, wear rates and volatility compared to conventional motor oils. Simple technical reasons are chemically stable hydrogen saturated molecular structure, lack f impurities such as sulfur, lack of wax and they do not contain reactive and unstable naphthenic (predominantly ring shaped hydrocarbons) ring structures. Additives work better and last longer in synthetic base oils.

Quote from Alan Amatuzio of Amsoil. Amsoil: A Close Look, Amsoil Action News / August 2005

ottotekteecher

One of the biggest advantages of Synthetic oil is that it can handle higher engine temperatures. If you have a car that is turbo charged the engine oil circulates in the turbo (for cooling the bearings) and the temperatures can be extreme. Especially when you shut the car off.(withT/C engines it is recommended that you idle the engine for 2 minutes to have a cool down period to let the eng oil cool/ circulate.
For our cars a premium oil AND filter will suffice. Personally I like synthetic oil as it will cushion eng parts better (keeps er quiet) and I like how synthetic additives clean the engine better. I DRIVE my car and feel better knowing the oil is not an issue. I teach in an auto shop and I have my guys change the oil AND filter every 5,000 kms. Overkill I know but I love this car and my students love working on it!!
Cheers, Rob

brn5150

Great posts by everyone. This is a battle that never seems to fade. I personally switched to Syn in my Maxima and my Altima previously. But, the point about the sand/dirt cant be beat.

The challenge I have (as I am sure others do as well) is I dont know how, or have the time/tools to change the filter only. Thus extending the life of Syn oil.

Great points by everyone. I just wonder how we all managed to survive 5-10 years ago when these forums didnt exist.

lobewiper

The matter of viscosity stability over time is of vital importance to oil quality. What initially is a 10-40 oil over time may become a 10-25 oil, for example. This involves the extent to which the oil is "shear stable." As run time increases, the molecular structures which maintain viscosity are cut (sheared) by the close tolerances of the engine's moving parts, and this is what causes viscosity breakdown over time. I learned this from a 1975 (?) Popular Mechanics article that showed minimal viscosity breakdown for Castrol multigrade over a 5000 mile test, when compared with several other oils. Since then, I have used Castrol GTX and changed oil and filter every 3000-3500. Just my $.02...

Monotaur

When I switched to Mobil 1 a few years ago, I also noticed that the engine got quiter. I also noticed that my MPG also increased slightly (maybe ~1MPG, but that's hard to tell really).

I also still switch at the recommended frequency because of deposit biuldups that occurr no matter which oil is used.

Daniel's Daddy

That may be good mechanics, but it's bad economics. If you don't change your oil, you risk problems that lower the resale value of your car. if the next owner benefits, then he'll pay for the benefit, right? On average you don't save anything by stretching out the time between oil changes.

Ray

xoomer.com

iTrader: (19)

I would have to partially disagree. While it is true that we change the oil to remove particles, dirt etc. They oil (used) looses its ability to lubricate. That is why its is recommended to change oil based on mileage and time. My uncle (good mechanic and car enthusiast) told me that I can run the car on synthetic for about 12K miles or 12 months. He stated that even if I do 4K a year, I should still change it after it being in the engine for 12 months (i do over 15K/year with 2 oil changes). Its is only logical because most of the "crud, particles, pollutants, etc" are removed by the oil filter.

I change my synthetic Mobil 1 with Mobil 1 filter every 6-8K miles. Every time I do it I am being told that I am wasting my money. Recently I checked my oil after 6K (39.5K on the car, driving hard) and it looks very clean. I was going to change it at 38K but said I can easily do another 3K on it. People on this forum have sent their used oil samples for analysis and were told they have about 40-50% of usefull oil life left. It wasn't because of dirt in the oil, it's because of the chemical agents that make up the syn***ic mix.

RHMax

After reading this thread yesterday, I changed to Mobil 1(5-w30) at 21k miles. Even though I change oil every 3k miles, the engine is definitely quieter and smoother with Mobil 1. I'll see how long I can go before next change.

MDS

I had to time to read about synthetics and found some interesting internet info.

Here are some quotes from Making Sense of Synthetic Lubricants, Don Stevens, http://www.firstfives.org/faq/oil/oilartcl.html

“Synthetic oils were originally developed more than 50 years ago and became widely used in jet engines. Less than -120şF ambient temperatures, 60,000 shaft rpm, and 500ş+F exhaust temperatures proved too much for conventional oils. Synthetics were created specifically to withstand these harsh conditions and to date every jet engine in the world uses synthetic lubricants. Amsoil introduced the first synthetic oil for automotive use in 1972 and have continued to be at the leading edge of development ever since.”

“Many companies have jumped on the bandwagon and have since released synthetic lubricants for automotive use and all are becoming increasingly popular for their superior lubricating properties, superior ability to flow at cold temperatures, and their ability to withstand high temperatures for extended periods of time.”


“There are two primary differences between synthetic oils and conventional petroleum oils. These are the base stock, or liquid, that makes up the volume of the oil, and the additive package. There are additives in all oils that enhance the wear resistance properties of the oil, enhance the ability of the oil to neutralize acids and combustion by products, and provide corrosion protection for the engine’s internal surfaces. The amount and quality of these additives vary from one oil brand to another and this is a very significant factor in the ability of an oil to adequately protect your engine in all driving conditions. As a general rule of thumb, the cheaper the oil, the fewer additives it has and therefore, the less able it is to protect your engine.”

According to http://p2library.nfesc.navy.mil/P2_O...ok/6_II_4.html, which was apparently written for military purposes:

“Synthetics are pure chemicals that do not contain the impurities or waxes inherent in conventional mineral oils. Conventional mineral oils thicken or thin dramatically with changes in temperature. As a result, manufacturers add thickeners to conventional multigrade oils to slow thinning as engine temperatures rise. Synthetic oils have high resistance to changes in viscosity due to temperature, and thus have less of a requirement for thickeners. As such they provide a heavier, more stable protective oil film for engine bearings and piston rings than that provided by similar SAE-grade mineral oil.”

Back to Making Sense of Synthetic Lubricants, Don Stevens,

“Synthetics almost always do have superior additives than petroleum oils…It enables the oil to last 3-5 times longer than conventional oil.”

“The synthetic base stock however, is of paramount importance. Synthetics are made up of uniformly shaped molecules with shorter carbon chains which are much more resistant to heat and stress. Synthetics can withstand temperatures of 300şF all day long.”

“Oil temperatures of 230şF to 250şF are not at all uncommon in driver’s education track conditions, particularly in early 911s with no front coolers or the marginally effective "trombone" oil coolers. These temperatures are also fairly common in air-cooled engines in summer time stop and go traffic with the A/C on. Further, temperatures on the cylinder walls and in turbos are often over 450° F for short periods of time.”

As a summary, according to http://p2library.nfesc.navy.mil/P2_O...ok/6_II_4.html,

Advantages:
• Synthetic oil lasts two to five times longer than conventional oil; thus, waste oil generation can be reduced two to five times if synthetic oil is used.
• Synthetic oils have high resistance to changes in viscosity due to temperature. As a result, they provide a heavier, more stable protective oil film for engine bearings and piston rings than is provided by similar SAE-grade mineral oils.
• Synthetic oil permits better cold weather performance and longer endurance.
• Manufacturers claim that synthetic oil yields better fuel economy, reductions in friction and wear, decreased oil consumption, improved performance, and extended drain intervals.


Disadvantages:
• Synthetic oil costs more than conventional oil.
• Since synthetic oil has improved fluidity, oil loss will occur more quickly through leaks because the thinner fluid will flow through a bad seal or worn ring.
• Some synthetic compounds are not compatible with conventional oils.
• The lower friction resulting from the use of a synthetic lubricant makes them unsuitable for break-in.

Final economic thought from Making Sense of Synthetic Lubricants, Don Stevens, http://www.firstfives.org/faq/oil/oilartcl.html

“Consider the following economic argument. If you change your oil every 3000 miles at a quick lube center at an average price of $23.00 per change, you spend $115.00 over 15000 miles. Most synthetic oil changes cost about $50.00 (much less if you do it yourself) on which you can drive 7500 miles very safely (a 7500 mile interval is within virtually all manufacturers recommendations). Over the same 15000 miles, only two oil changes are required for an investment of $100.00.”

White Shadow

iTrader: (11)

The key to maximizing the benefit of synthetics is that you shouldn't change it as often as dino. If you change dino oil every 3000, use the synthetic and change the filter only at 5000 and the oil and filter both at 10K. Then it will give you superior protection and also cost less than dino over the long run. You still have clean oil and don't have to worry about sludge and deposits in the oil. Some manufacturers actually recommend doing your oil change schedule this way.

Also stop being so damn cheap. If you love your car consider it the normal cost of maintenance to use synthetic no matter how much more it costs. I don't consider it a luxury, I consider it a necessity. Every car I've had has gotten me over 200K without any trouble.

xoomer.com

iTrader: (19)

...and thats they way the cookie crumbles. Amen

madmik

iTrader: (1)

I also use Amsoil. I just love the sound and the feeling of the VQ between 3-6k. I don't want the engine to fail because oil breakdown under stress or high temp. Amsoil had one of the best shear test results and is available at my nearby auto part. It also reduces friction, thus heat and less metallic particle released into the oil.

From what I read, the Moly and other fine suspended particles left in the oil actually help create a better lubricant as times go on, but not forever.

For the price and value, I think nothing beats fresh dino oil with a good oil filter. I am actually a Pennzoil fan but think that Mobil-1 is also great. For my VQ, Amsoil is my insurance. New filter every 4k, new oil around 8k.

jsuggs

:-) Yepper ! I do my oil myself... the dealer does once in awhile just to let them know I still around.. NO DOUBT about it ... spend the time and money ... if you divide the total cost per year by 12 ... its not too much .. give up that soda and candy to pay for it ... I have two cars that get this treatment .. a 2002 CamaroSS and my Max ..