Oil Intervals Longer Than One Year-- Thoughts??

[Hermes]

My basis is personal experience.

I get better fuel economy on my cars and on occasion have even seen my friends cars pass smog merely by changing the oil. It makes a difference even if you are using modern fully synthetic oil to keep your system fresh, although not as urgent as it used to be

[danewilson77]

My basis is personal experience.

I get better fuel economy on my cars and on occasion have even seen my friends cars pass smog merely by changing the oil. It makes a difference even if you are using modern fully synthetic oil to keep your system fresh, although not as urgent as it used to be

What is the longest you've kept synthetic oil in one of your BMW'S (time/mileage)?

I guess, what ages/mileages are you comparing the better fuel economy to?

"No flamesuit required"

[Hermes]

The longest I ever kept oil was appx 1yr/10k. The shortest was 3k. I now do my changes at 5k on the E46/E38, and 3-5k on the older cars. The older cars use semi synthetic so it's not exactly the same but still gives me mpg changes when I change the oil.

I drive pretty much the same route every week and the same speed/style of driving. My mpg will go up about 1/2-1 mpg when I change my oil in the E46, less in the E38. The E21 sometimes has jumped 4 mpg when I change the oil even at just 5k intervals.

As for my buddy with smog, he tried everything he could think of and was just outside of passing. I went over and we realized he hadn't changed the oil in about 3k (still a reasonably short amount for an E34) but it had been a while since he didn't drive the car much, and just doing that he managed to pass.

Basically I agree that you don't have to change oil at the frequencies that the lube places say, but there is still an advantage to keeping fresh fluids in your car.

[BCS_ZHP]

Dane, when we had pleasure boats, the marina mechanic recommended an oil change every year no matter how many hours of use you didn't accumulate. The mechanic explained to me that despite non-use and break down of the oil, with every seasonal temperature cycling some moisture from the air is dropped into your engine in the form of condensation from those temperature changes. He said it's not much, but it is some minuscule amount of water droplets getting into your engine. If you run your engine regularly, those condensation water droplets get consumed, vaporized by the heat cycling If you don't use the engine regularly, the water droplets can concentrate on bare metal surfaces like rod bearings, crankshaft journals, camshaft lobes, and they may form rust. He admitted it was very minor but change the oil yearly and you'll know any water droplets are not in your engine. Bruce

[danewilson77]

......They recommend I leave the oil in for 10k miles, even if it is in for longer than a year.

Dane, when we had pleasure boats, the marina mechanic recommended an oil change every year no matter how many hours of use you didn't accumulate. The mechanic explained to me that despite non-use and break down of the oil, with every seasonal temperature cycling some moisture from the air is dropped into your engine in the form of condensation from those temperature changes. He said it's not much, but it is some minuscule amount of water droplets getting into your engine. If you run your engine regularly, those condensation water droplets get consumed, vaporized by the heat cycling If you don't use the engine regularly, the water droplets can concentrate on bare metal surfaces like rod bearings, crankshaft journals, camshaft lobes, and they may form rust. He admitted it was very minor but change the oil yearly and you'll know any water droplets are not in your engine. Bruce

Thank you JP and Bruce for sharing your personal experiences. It helps a lot as I may reach KGOCS soon.

I'm also wondering how legit these guys are if they are making a solid recommendation to leave it in greater than a year. I don't understand why they just don't play it safe and recommend 1 year or less? I would think they would know about...

1. The possibility of lost fuel economy.

2. The possible adverse effects when marginally failing smog.

3. The formation and falling away of small condensate droplets in various lubricated portions of the engine....how ever miniscule they might be.

"No flamesuit required"

[kayger12]

Dane, when we had pleasure boats, the marina mechanic recommended an oil change every year no matter how many hours of use you didn't accumulate. The mechanic explained to me that despite non-use and break down of the oil, with every seasonal temperature cycling some moisture from the air is dropped into your engine in the form of condensation from those temperature changes. He said it's not much, but it is some minuscule amount of water droplets getting into your engine. If you run your engine regularly, those condensation water droplets get consumed, vaporized by the heat cycling If you don't use the engine regularly, the water droplets can concentrate on bare metal surfaces like rod bearings, crankshaft journals, camshaft lobes, and they may form rust. He admitted it was very minor but change the oil yearly and you'll know any water droplets are not in your engine. Bruce

Good info, but this oil was in for a year through both summer and winter and the analysis showed zero water in the oil.

It seems that a lot of the conventional wisdom isn't necessarily based on data or empirical evidence.

It's an interesting discussion.



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[wsmeyer]

I would do what Blackstone recommends. If you're not comfortable with 10k go with 7k, send a sample of that to Blackstone and see how that goes.

Oil does break down over time and it's ability to lubricate and absorb contaminants diminishes, but this can be quantitatively measured. That's what Blackstone does. You tell them what oil you put in and how many miles you drove and they compare the state of your oil to that of new oil. That's the whole point of their analysis.

When I first started driving in the 80's you would hear 2k miles as the recommended interval, not even Jiffy Lube would recommend that frequency now lol. The advancements in metal coatings and more precise manufacturing have reduced the amount of metal particles introduced into the iol via friction have decreased to the point where the lubrication properties of motor oil are lost to breakdown faster than contamination. And the synthetic additives in the oils we use have greatly decreased the rate of breakdown.

Just my .02 cents as they say.

[danewilson77]

I would do what Blackstone recommends. If you're not comfortable with 10k go with 7k, send a sample of that to Blackstone and see how that goes.

Just my .02 cents as they say.

But they said to run it for greater than a year? Really?

"No flamesuit required"

[az3579]

I'd go with the experts. They see the things that actually *do* happen.

Just because this kind of stuff "can" happen doesn't mean it will. For all we know, the likelihood of it happening is the same likelihood of winning the jackpot on the lottery three times in a row.

[Avetiso]

Oil withstands thousands of heat cycles and constant abrasion over the course of its life. It may break down over time, but I think most people don't realize just how slowly this happens (plastic, anyone?).

Assuming there is no immediate cause, oil will not degrade in and of itself fast enough to require a yearly change. You could leave it in your engine for two or three years, if not more, ASSUMING:

The engine is completely sealed and there is nothing else that could potentially degrade the quality outside of regular causes (and of course you haven't driven on it enough to warrant a change).

Sure, you could play it safe and change it every year regardless, and considering the cost, might as well. However, that doesn't make it right, nor does it make anything better.

Keith said it right. It's conventional wisdom at best. You can make the argument that it helps you sleep at night, but you can't make the argument that leaving it in there longer hurts it, because you can't prove that.