Interesting info regarding oil drain interval

http://www.sae.org/technical/papers/2007-01-4133

Abstract:

Engine oils are subjected to a series of industry standard engine dynamometer tests to measure their wear protection capability, sludge and varnish formation tendencies, and fuel efficiency among several other performance attributes before they are approved for use in customer engines. However, these performance attributes are measured at the end of tests and therefore, do not provide any information on how the properties have changed during the tests. In one of our previous studies it was observed that engine oil samples collected from fleet vehicles after 12,000 mile drain interval showed 10-15% lower friction and more importantly, an order of magnitude lower wear rate than those of fresh oils. It was also observed that the composition of the tribochemical films formed was quite different on the surface tested with the drain oils from those formed with fresh oils. The objective of this investigation is to demonstrate how the friction and wear performance changed with oil drain intervals. A fleet of three vehicles was run in Las Vegas and oil samples were collected at various drain intervals from 3,000 miles to 15,000 miles. As in the previous study, the results showed that the aged engine oils provide lower friction and much improved wear protection capability. These improvements were observed as early as the 3,000 mile drain interval and continued to the 15,000 mile drain interval. The composition of tribochemical films formed on the surface with the 3,000 mile drain interval is similar to that formed with the 12,000 mile drain interval as seen before. These findings could be an enabler for achieving longer drain interval although several other factors must to be considered.

Moral of the story: Those of you who change oil every 3-5k to be on the "safe side" are being counterproductive.

Don't change it too often and increase wear.

Don't change it too seldom and increase wear.

There's a sweet-spot, if you will.



BTW - Thanks to jpr for initially sharing this article.

How interesting! One could extract a lot of useful from that article

Thanks for sharing

So... the best thing to do is to talk your buddies into letting you "help change their oil" at 3-5,000 miles, and then offer to "dispose of it" for them for free. You just don't have to tell 'em you're going to "dispose of it" by pouring it into your engine!

my magic number is 7500 miles

bump.

waaay too many people need to see this.

Pure BS, for what it cost to analyze my oil, I just change it and you can see the smile on the engine 5K me majic # plus I enjoy doing this

Nice...

I'M NEVER CHANGING MY OIL AGAIN!!!!!!!!










Seriously tho, looks like I may be switching to once a year, or around once every 10k-15k miles, with a biannual filter swap.

Originally Posted by BMWespresso

Pure BS, for what it cost to analyze my oil, I just change it and you can see the smile on the engine 5K me majic # plus I enjoy doing this

you dont have to get an analysis. I've done one so far, and i've got a few more to do. So far it's pointing to about 9-10k. (on mobil 1 0w-40)

On my next change i'm going to let the SI count down to 5k miles and see how it's doing at that point. Using the SI is the best way to determine oil life to begin with, but i wasnt thinking about this last time i changed and forgot to reset it . So mileage is all i have to go by this time...

Originally Posted by BMWespresso

Pure BS, for what it cost to analyze my oil, I just change it and you can see the smile on the engine 5K me majic # plus I enjoy doing this

This has been argued for ages.

I change mine every 5k and my bimmers are at 109k, 139k, my last bimmer was at 178k before I sold her, and my jeep is at 230k miles right now. I'm not worried.

Originally Posted by habbyguy

So... the best thing to do is to talk your buddies into letting you "help change their oil" at 3-5,000 miles, and then offer to "dispose of it" for them for free. You just don't have to tell 'em you're going to "dispose of it" by pouring it into your engine!

I remember reading about an service technician that brought used oil home from his work and used it in his own cars, because he found it just a waste when people insisted the oil be changed every 3-5000 miles when he knew the oil would be good for 10-15,0000 miles.

Originally Posted by BMWespresso

Pure BS, for what it cost to analyze my oil, I just change it and you can see the smile on the engine 5K me majic # plus I enjoy doing this

LOL, you think you are smarter than the SAE? Wow. Well, before I say anything else mean, do you use Mobil 1 0w-40 and if you do, could you ship it to me if I pay for shipping?

Excellent article. So the lubricity increases as the oil gets more mileage. That means the longer the oil change interval the better. I am definitely sticking to my sweet spot of 45k miles or 6 years interval.

Yah but..

Ever had one of those cars that you could feel a smoother/quicker/ whatever word that describes improvement right after your oil change and then it slowly fade away as time went by?

I like to do it every 7500 which for me is twice a year. i do it once i put the skis away and then i do another in the fall when i take the skis out.

Originally Posted by ETA

Yah but..

Ever had one of those cars that you could feel a smoother/quicker/ whatever word that describes improvement right after your oil change and then it slowly fade away as time went by?

Yes, that's called the placebo effect. It happens after spark plug change, coil change, new floor mat, or washer fluid change. Sometimes a pair of new shoes has that effect too.

Originally Posted by TKC

This has been argued for ages.

I change mine every 5k and my bimmers are at 109k, 139k, my last bimmer was at 178k before I sold her, and my jeep is at 230k miles right now. I'm not worried.

Yea you're right. No one knows more than you.

Originally Posted by jeffro3000

Yea you're right. No one knows more than you.

Especially automotive engineers who publish research articles.

Good article jeffro

so you guys agree with this but you do not agree with BMW recommendation regarding lifetime transmission fluid?

Originally Posted by GoingNuts

Excellent article. So the lubricity increases as the oil gets more mileage. That means the longer the oil change interval the better. I am definitely sticking to my sweet spot of 45k miles or 6 years interval.

*whoooosh*

there it went. right over your head.

I think the forum would be better off if you refrained from posting in this thread. This is about data backup up by research. You have nothing of this sort.

Originally Posted by GoingNuts

Yes, that's called the placebo effect. It happens after spark plug change

Spark plugs: Not placebo.

The rest: Placebo.

My car runs better after I wash and wax it.

Originally Posted by eu_miki_80@yahoo.c

so you guys agree with this but you do not agree with BMW recommendation regarding lifetime transmission fluid?

maybe we could, if you explain us what do the two have to do with each other?