Synthetic oil

Synthetic oil. Is sit better than conventional oil? How long between oil changes can you go?

Don’t buy synthetic oil to extend your oil change intervals. Most synthetic oils have the same “additive” package in them as regular oil. The additive package (25% or so by volume) largely determines how long you can go between changes.

On the other hand if you drive in very cold weather, very hot weather , or tow a heavy trailer, the qualities of synthetic oil make themselves known in that they resist high temperature breakdowns, they flow well at very low temperatures, allowing easy starts and rapid oil circulation. And their superior film strength make them ideal for heavy loads. If none of the above apply, and your car’s manual says it can use regualr oil, stick with it. Even if you could extend the drain interval by 25%, the extra 50-75% in cost would not make it economical.

There are some extended drain synthetics, such as Mobil 1 Extended Drain, with a much larger additive package in them; those oils allow a longer drain interval, but they are quite costly. European cars such as VW and BMW need those special and costly oils, as specified.

We get asked this question at least once a week

 [i] Synthetic oil. Is sit better than conventional oil?[/i]  

 Define better?   It is at least as good, but it also is more expensive.  

  [i] How long between oil changes can you go?[/i] 

 What ever is listed in your owner's manual.  It likely will list both a time and a distance.  You change it at which ever comes first.

   Synthetic does not really change the above, although some people might increase the distance, but I would recommend sticking with the original recommendation in the owner's manual.  Being synthetic will not prevent condensation or other pollutants from getting into the oil.

What ever is listed in your owner’s manual. It likely will list both a time and a distance. You change it at which ever comes first.

Why do some people say this, and then when an owners manual says to change the oil when an OLM system says to change it, or if the manual says change it at 10k or 15k miles, then suddenly the owners manual shouldn’t be paid any attention to?


I consider the owners’ manual to be a listing of the mileage/time at which the oil is DUE. You can always change the oil BEFORE it’s due. Personally, I consider 10K or 15K to be longer than I’m confortable with, and in those questions wherein someone has an OLM that hasn’t yet designated a change and they’ve gone beyond 5K, I’ll recommend changing it. Oil is cheap, engines are expensive, and my goal is to extend the life of the engine rather than the life of the oil.

In summary, when the owners’ manual suggests a longer period than I consider prudent I’ll recommend more frequent oil changes.

csa had a good link a couple weeks back about these long oil change intervals. I personally don’t like to keep my oil in the car longer then 5k miles. Has anyone done a study to see how well these engines are after 100k, then 200k, then 300k miles. I know for fact that on almost any engine…5k mile intervals will keep an engine running well past 250k miles. How long the same engine last with 10k mile oil change intervals.

And these oil monitoring systems. How accurate are they?? What does it mean when the oil is 40% life left. Does it mean the oil is still protecting your engine just as well when it there’s 100% life left?? These system also only keep mileage and temperature. What about contaminates?

I’m still very skeptical. Your vehicle is far too costly to just HOPE the extended oil change intervals work…or HOPE the Oil Monitoring system is calculating everything correctly.

I know that the 5k mile oil change interval works. And the cost difference between changing the oil every 5k miles and 15k miles is NOT going to break the bank.

Everything you every wanted to know about oil (but were afraid to ask):

I think synthetic oil shines in high mileage, frequent use where vehicles are allowed to run up to heat for prolonged periods which discourages sludge formation. This includes excessive idling as well. 10K oil changes then make sense. Otherwise, just using it so you don’t have to change your oil for two years in a low/medium mileage average use car makes little sense to me and can increase wear and not the other way. Changing it at regular oil intervals makes little sense to me economically as regular oils are fully capable of excellent service under normal conditions.
Using synthetics in police cruisers and cabs is an excellent way of of saving the taxpayers money and increase profits for cab owners. In my limited experience it’s not unusual for the service life in miles of these hard use vehicles to be equal to or greater than that of the well maintained family car with more frequent changes, synthetic or regular. One retired cop I know uses synthetic and 10k changes in his 200k plus Camry. But it is used for extended trips/use and NOT hopping around in town.

I Use Mobil-1 Extended Performance Oil, Exclusively, In Our Family’s Cars. It Makes More Sense Than Ever, Relatively Speaking.

I don’t go longer than 5,000 miles between oil changes, regardless of what the car’s oil monitor says. I change my own oil because it fits our schedule better and I know it’s done correctly.

It gets very cold here in the winter and gets quite hot in the summer (Also, the temperature out on that hot asphalt in summer exceeds the ambient temperatures reported.) and we do some extended idling (My wife and daughter start the cars and let them “warm up” in the winter. Try and convince them otherwise when the car comes with remote start. Most people operate their vehicle in some type of “severe” conditions once in a while, as we do.

An oil change used to cost me about the same as a gas fill-up. We could require ten gas fill-ups between changes. The oil services were 10% of gas/oil expenses. Now an oil change costs about half of what a gas fill-up costs. Oil service now runs about 5% of gas/oil expenses. In the scheme of things up-grading to Mobil-1 Extended Performance is a very minor car operating expense. We drive 30,000 + miles / year on our cars and it probably runs an extra 100 bucks per year, per car, cheap insurance. The peace of mind alone is worth it.

I’m cheap, but I find it silly to spend tens of thousands of dollars for a car and thousands of dollars for gas and then skimp on the car’s life-blood, it’s lubricating oil. I just go with Mobil-1 Extended Performance and don’t worry if the conditions are “Severe” or not. The cost difference is so little that it’s a “no brainer” to me.

For folks interested in making the switch, here’s Mobil-1’s link:


It’s not just oil changes, BC.

Transman, and several others, recommend changing the transmission fluid every 30,000 miles instead of the 60,000 or 90,000 recommended in some owner’s manuals.

Does your owner’s manual recommend a 90,000 or 105,000 mile timing belt replacement interval? Many people recommend 60,000 miles instead.

What about your tires? Do you run them down to the 2/32" or 4/32" legal tread depth requirements, or do you replace them before they get to that point? I prefer to replace my tires before the need is dire.

What about brake fluid and brake pad wear? Do you service your brakes a little sooner than recommended for safety sake? I try to.

Makes the opinions here seem tame; the sociology alone on this site can be interesting reading…

From The Department Of Redundancy Department: Twotone Already Supplied The BITOG Link, Above.

sorry; please fire when ready.