so you think your modern fuel injected/computer controled car still fills the oil with fuel?

so all those oil analysis done on newer cars running todays oils showing that the oil is fine after 7500+ miles are all wrong?

According to a special report released by the Motor & Equipment Manufacturers Association (MEMA), synthetic motor oils are key to extended drain technology: “Extended drain technology is primarily based on the availability of synthetic oils. While the additives in conventional, non-synthetic oils allow them to function longer than the tradition 3,000 miles, it is primarily the synthetic base stocks that allow the oil to last much longer. Synthetic oil offers many advantages in durability versus conventional petroleum oil and it is all based on the synthetic oil’s superior heat and oxidation resistance.

Synthetic oil is more accurately controlled at the molecular level and therefore can be engineered to resist the forces in an engine that work against oil durability.”

Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan.

A look at many recent model owners manuals reveals a recommended 5000 to 7500 mile oil drain interval, while European vehicle manufacturers recommend even longer drain intervals.

The implications of the extended drain interval on the automotive aftermarket are mixed. There are two clear losers – the quick lube industry and the oil filter industry. According to a past National Oil and Lube News, Marc Graham, then president of Jiffy Lube International, said that for every 100-mile reduction in fast lube customers’ oil change intervals, the industry could realize $105 million in sales. Clearly, the converse is true, so a widespread extension of drain intervals would have an immediate and negative impact on the industry. This could be partly offset by the need for synthetic oils which traditionally command a premium that might help compensate for the lost volume.


The only real way to determine whether oil is truly in need of changing is to have an oil analysis performed. Since most people don't want to bother with this, it's acceptable to err heavily on the safe side and simply follow the manufacturer's recommended change interval for severe service. There are still a few cars that specify 3K intervals for severe service, but not many. If you look at countries other than the U.S., the oil recommended change interval is much higher than even the normal interval specified by vehicle manufacturers in the U.S

Those analysis don't prove much of anything as every car is different. Cars with 100,000 miles are going to have a little less ring seal and get a little more metal particles in the oil than a 10,000 mile engine and the way every engine is driven will change how fast it contaminates oil in the future so a blanket statement like "you can go 10,000 miles on our (snake) oil" are foolish statements desighned to sell you their kind of oil.

Also as for the manufactures stateing their cars can go for sooooooo long on an oil change are kinda pulling the wool over your eyes also. If you look in the owners manual fine print then 95% of drivers never drive in "normal" conditions and if you don't drive in their "normal" conditions you have to change the oil every 3000 miles. Another little trick of the makers is to make the sump bigger and obviously it takes longer to contaminate 6 qts of oil than 4 qts in the older engines.

Above all of it there is still a trade off because as soon as you start driving on your fresh oil change there is contaminates in it and they increase as long as you drive, you just have to make a trade off about how long you want your engine to last, for example you could change the oil and coolant every 1000 miles under normal driving and most engines would last longer than the owners will live but you got to decide that for the price of 5000 oil changes over the course of 500,000 mile you could buy a lot of motors, just pick your poisen and decide what compromise you want to make

For me I change it every 3000 religiously and I just use the generic brand as long as it has the latest API rateing and am happy that I have cars go over 200,000 and 300,000 miles without blowing motors. When the motor is newer you can let it slide a little longer but as the engine wears it gets contaminated faster and should be changed more frequently depending on how long you want it to last.

Thats not what I said at all, many of the synthetic oils are just fine after 7500 or better, but the contaminates are still in the engine

Contaminates… You guys need to think outside the box of the limited abilities of traditional paper cellulose oil filters…

Paper vs. Glass Oil Filter Comparison - link

we do try to get customers in a high mileage/Synthetic oil, older people are stuck in there ways and don't want to switch, no matter what facts you show them, younger customers do switch or their car came with Synthetic and don't think they have to do anything else, this is where the problem is, maybe it's a yuppie thing. anyway thats how we can out motors more often. Can i sell you good Valvoline Oil??

Hey CS ...

....a 3k mile oil-change-interval ? .... whatever happened to that proposed 25k "interval" ?

... ...

This is probley a dumb question but... If loose oil contaminants are the main concern with changing the oil at specified intervals, what would happen if you just changed the filter to a super good filter after about 5000 miles, topped the oil off, and did a complete oil and filter change about every 10000 miles?

Just a question, how does it fare?

Chuck welcome aboard and there are no dumb Q's. Fire away . The problem is that filters (even the best) only catch some of the particles plus there's the problem of the soluble contaminates like acids/sludge/carbon etc. And even if the solubles were dealt with in some fashion you still wouldn't be able to go too small on the filter material micron size as you'd reach a point where the flow is restricted. It's comparable to when you were kids and your mom would clean several of you and your siblings in the tub one right after another & after so many kids in there you just reach a (saturation) point where the only thing left to do is change the water

Actually Chuck Amsoil makes a filter system for exactly what you are talking about. All you do is change the filters(two) and top off the oil.
These are not your ordinary run of the mill filters.
AMSOIL EaBP Filters have an efficiency of 98.7 percent at two microns. At normal operating RPMs the EaBP Filter will filter all of the oil in a typical five quart sump in less than 10 minutes.

For more info Amsoil by-pass filter system.

Hay CS ..... you sure have some DATA ......

BUT WHAT about the "contaminants" such as raw fuel, condensation and piston-ring blowby?

Are you suggesting that the "glass-media" filters will FILTER that all out?