Oil: I'm Not Convinced It Ever Needs To Be Changed

[crazyal]

I worked at a company that had a 3/4 GMC with a 350 in it. They had the truck for years and the oil never got changed. The oil in it was the same oil it came with the day they bought it (used with 50K). After about 30k miles it started using oil, not really smoking but it would need a quart every 5k. After about 50k it needed a quart added every 1k. One day the owners son decided that it was time to change the oil. What came out was almost a paste, black as tar, and stained his hands for a week. It was winter time and the truck didn't like starting in the cold. Someone needed to use it, got it started, and put something on the gas pedal to keep it running to warm up while he went inside. After about a minute it spun a bearing. When they pulled the motor it was quickly determined that rebuilding it was not an option because of all the damage. Of course the filter never got changed either.

The colder the weather the more important oil changes are. Conventional oil has additives to thin it out when cold, that's what breaks down. Since most wear happens when you start a cold engine you want those additives to work. Now if you never change the oil and things get worn and loose thick oil may flow easier and lubricate the engine better than what it would do in a tight engine. With a diesel, because of the blow by, it could also thin the oil some helping it flow better. But if you ever do change the oil it's very possible that your oil pressure will be too low to get oil everywhere it needs to. To me it's better to prevent the damage being done than live with it after the fact.

 

[hosspuller]

Lubrication is a function of hydrodynamics. If the oil film keeps the metal from touching, it's doing the job. It's the side effects we're avoiding by changing the oil. Filters are not 100% efficient, combustion products are acid, oil does break down into sludge and gums, viscosity changes through shear. Change the oil and one gets rid of the bad stuff. The oil passages stay clear, the bearings don't get pitted, wear is minimized.

 

[CBW1999]

Newer cars have the ability to monitor operating conditions and determine life span of the oil. When the "change oil" light comes on, typically there is about 10% "life" left to the oil.

In our van this can be anywhere from 3500 miles on up (haven't actually kept track) to more than 7500 miles. The owners manual states there is no advantage to changing the oil before the "light" comes on. The only caveat is changing the oil at least every 12 months.

 

[STROIL]

Ok, that brings up the question of the "change oil light" that is common today on a lot of cars. I know this isn't exactly the topic of this thread, but it's closely related.

The question to any experts out there is this: Is it possible that these new cars have some ability to actually monitor and report on the performance ability of the oil? In other words, could these cars possibly be doing some kind of chemical analysis of the oil, and then notify when the effectiveness of the oil falls below some threshold?

I find that hard to believe.

It seems to me that the change engine oil notifications or "change oil lights" can only measure two things: 1. elapsed engine hours since the last oil change and 2. The vehicles milage since the last oil change. Both of which could be done manually, the way we've all done it for years.

Am I wrong?

 

[murphy1244]

Ok, that brings up the question of the "change oil light" that is common today on a lot of cars. I know this isn't exactly the topic of this thread, but it's closely related.

The question to any experts out there is this: Is it possible that these new cars have some ability to actually monitor and report on the performance ability of the oil? In other words, could these cars possibly be doing some kind of chemical analysis of the oil, and then notify when the effectiveness of the oil falls below some threshold?

I find that hard to believe.

It seems to me that the change engine oil notifications or "change oil lights" can only measure two things: 1. elapsed engine hours since the last oil change and 2. The vehicles milage since the last oil change. Both of which could be done manually, the way we've all done it for years.

Am I wrong?

My 09 merc does it by miliage.

 

[RaydaKub]

When I was a kid, we had a neighbor that used a <can't think of it now> brand oil filter on all his cars. The filter was just a shell and you put a fresh roll of Charmin in the shell and add a quart of oil every 3000 miles. Yeah, you read that right, toilet paper (but only the GOOD stuff). I have no idea how many miles they ran with that, but it was a number of years.

My dad declined the offer to add said filters to our cars.

 

[sixdogs]

My neighbor is notoriously bad at changing his oil and has gone through a few heads and maybe three engines in vehicles and two tractors over the 10 years I have known him. The vehicles were American made and under 65,000 miles or so. One tractor conked out at 800 hours and the other I don't recall. I've been very good at maintenace for my stuff and in 63 years of life--and a list as long as your arm--I've never had any problem. Never even had an injector off and I use my stuff.

Edit--I'll add that in my lifetime I believe oil will be developed that will not need to be changed in the life of a typical car life, say 100,000 miles. I think it's getting close.

 

[CBW1999]

Chevy venture does it by engine operation information that the computer analyzes, not the oil itself.

http://www.google.com/url?sa=t&rct=j&q=gm%20oil%20life%20minitor&source=web&cd=3&cad=rja&ved=0CDUQFjAC&url=http%3A%2F%2Fassets.cobaltnitra.com%2Fteams%2Frepository%2Fexport%2F975%2Fc7820afba1004895010145efa6b30%2F975c7820afba1004895010145efa6b30.pdf&ei=8IVTUMLSN6u-0QHdj4HQBQ&usg=AFQjCNFAYU4ZN0wIov4Tz8MGKWVdbucIWQ

This pdf explains it well

 

[Gary Fowler]

Ok, that brings up the question of the "change oil light" that is common today on a lot of cars. I know this isn't exactly the topic of this thread, but it's closely related.I find that hard to believe.

It seems to me that the change engine oil notifications or "change oil lights" can only measure two things: 1. elapsed engine hours since the last oil change and 2. The vehicles milage since the last oil change. Both of which could be done manually, the way we've all done it for years.


Am I wrong?

According to my GM book, the computer does a bit more than record mileage. It doesnt do a chemical analysis but uses the on board computer to determine how hard the engine has labored, how much high rpm time it has seen etc. Using it to pull trailers etc will cause the computer to want oil changed quicker mainly I think because it shows more engine revolutions. So it isnt only monitoring the mileage. My 2007 Chevy 1500 oil was changed in June 2011 and it is still about 10% life left. Since it stays in enclosed garage when not used, I am not going to change it till it says its time even though it has been over a year. I used full synthetic 10w30 in it and will do the same when the computer says to change it. Oil filter and oil are on standby. My minimal mileage drive is about 20 miles so when I do use it, it gets hot enough to boil out any water accumulated. Most mileage is put on in 400 mile or more trips but it sets in the garage for weeks at a time without moving.

 

[Bluegill2]

Ok, that brings up the question of the "change oil light" that is common today on a lot of cars. I know this isn't exactly the topic of this thread, but it's closely related.

The question to any experts out there is this: Is it possible that these new cars have some ability to actually monitor and report on the performance ability of the oil? In other words, could these cars possibly be doing some kind of chemical analysis of the oil, and then notify when the effectiveness of the oil falls below some threshold?

I find that hard to believe.

It seems to me that the change engine oil notifications or "change oil lights" can only measure two things: 1. elapsed engine hours since the last oil change and 2. The vehicles milage since the last oil change. Both of which could be done manually, the way we've all done it for years.

Am I wrong?

My wife's car also does it by mileage. It can be set ay 3k, 4k, 5k, etc.