Oil Change = Engine Failure ???

[rick3000]

Hi,
So I just got back from getting my oil changed, and my mechanic mentioned something very interesting. He told me that Porsche and all these new cars that say to change your oil every 15-20k miles are crazy. He said it doesn't matter what car you have you should change it every 3k miles, 4k at the most. He also said that cars that change the oil at those large intervals are more likely to have an engine failure, he told me about a Cadillac, a Cayenne, and few other cars where the owners did the 15k mile oil change intervals and they all needed engine replacements (the Cayenne at 50k miles).

So do you guys think there is a valid connection between your oil change interval and your likely hood of an engine failure?

-Rick

[blinkwatt]

How do you explain the Boxsters on PPBB with over 200k on them?

I take what Porsche has to say over any 1 mechanic any day.

[Boxtaboy]

Originally Posted by blinkwatt

How do you explain the Boxsters on PPBB with over 200k on them?

I take what Porsche has to say over any 1 mechanic any day.

FWIW, the guy on PPBB who has over 200k on his 02 Boxster does his oil changes every 5k miles though. Used M1 0W-40 exclusively until just recently when he changed weights to a 5W, I think.

[Lil bastard]

Oils are better, Fuels are better, and engines are better than they were in the past.

All 3 of these things allow oil change intervals to be extended. The question is: By how much?

Most Service Intervals are optimized by car mfgrs. for marketing purposes - to make the cars easier to sell.

But, most manufacturers, incl. Porsche state in their owners manuals that these intervals are for Ideal conditions, which almost no one encounters. TRhey further usually state that for Severe conditions, these intervals should be shortened. Because they cannot know everyone's driving habits, they cannot say by how much, since each one's experiences are different.

Frequent short trips (under 10 mi.), Stop&Go driving, Interstate driving, wet climates, dry climates, hot climates, driving past construction zones or projects, poor or eratic fuel quality, hard driving, heavy loads all constitute what automakers term Severe conditions.

So, it's safe to say that going 20k mi. between changes is not recommended, even by the carmakers themselves.

You need to use your own judgement. 7500-10k mi. covers the bases pretty well, you are doubling to tripling the previously accepted interval.

But, you really need to consider the interval differently for each batch of oil you use. If you have a rainy season, or hot season, or any changes during an interval, say driving hard, or your daily route is under construction, you may want to shorten the interval. Likewise if any of your normal conditions change for the better, you could extend an oil change a few thousand miles too.

Just remember the old addage: "Oil is cheaper than engines"

[Perfectlap]

I sometimes wonder about the element of time, or how long the engine is running.
Add up all the time waiting at stop lights, intersections, drive thrus, stand still traffick where little if any mileage is racked up. Add up all that time over the course of an engines life. I'd be curious to see how many hours are actually 'driven'. That alone makes me think the oil interval is too long.

What I would really like to see is some sort of telemetry that analyzes the oil and relays to the driver when its begun its decline. But then that might put some folks who rebuild engines out of work!
Seems like it would be good for the oil industry though..

[jmatta]

No offense, but I'd like to know the dollar value exchanged between Porsche and ExxonMobil for the "exclusive" fill sticker. If you trust a Porsche engineer, then you also trust the accountant that made him trim the parts back to save a few Euros on each car.

I've read enough independent study (as well as track experience) to know that changing your oil often can be critical to engine life. The high mileage guys will tell you the same thing, with out getting into which oil is better. I know the brands I prefer and M1 is not one of them, nor would I ever recommend it to a friend.

[Lil bastard]

Originally Posted by Perfectlap

I sometimes wonder about the element of time, or how long the engine is running.
Add up all the time waiting at stop lights, intersections, drive thrus, stand still traffick where little if any mileage is racked up. Add up all that time over the course of an engines life. I'd be curious to see how many hours are actually 'driven'. That alone makes me think the oil interval is too long.

What I would really like to see is some sort of telemetry that analyzes the oil and relays to the driver when its begun its decline. But then that might put some folks who rebuild engines out of work!
Seems like it would be good for the oil industry though..

Good point! And it's idle time which is most abusive to oil because of high temps and poorer combustion.

On many other machines - aircraft, boats, heavy machinery, it's the hrs. or time interval, not distance, which are counted and the basis for most service intervals.

You could add an hour meter to the car. It's be simple enough to wire one in and there are many to choose from - Hour Meters , even Sunpro offers an analog and digital ones - SunPro ... all less than $50.

'Course then the arguement would shift to 'how many hrs.?' instead of 'how many miles?'... guess you can't win.

[mikefocke]

to a sample which consisted of quantity 1. Maybe MarkW just got one of the good engines. ..one that wouldn't fail under any circumstances.

Though I do agree with the 1 year or 5k miles whichever comes first but I do it on the basis of seeing what multiple people who have torn down these engines recommend.

BTW, if you reading this know anyone in the Atlanta area who is contemplating a clutch change on a later than '00 986 or 996 they should get in touch with me. I may have an interesting offer for them.

[rick3000]

I am not so sure his business is slow, he had three Bentleys, two Rolls Royces, a Ferrari, a half dozen Jaguars and Mercedes, a couple of BMW's, a 911, and my Boxster at his shop.
I really only posted this to see what everyones opinion on this is. There does seem to be some correlation, but it is debatable what the oil change interval should be. I think 5k is the interval I will be going with from now on.

Originally Posted by rick3000

I am not so sure his business is slow, he had three Bentleys, two Rolls Royces, a Ferrari, a half dozen Jaguars and Mercedes, a couple of BMW's, a 911, and my Boxster at his shop.

Rick, that's because the Bently, Rolls Royce, Ferrari, and Jaguar (Ford!) guys believe your mechanic. Porsche guys are smarter than this, and higher up in the food chain! This well known and completely documented

[crios]

I do believe there is a correlation...drag race cars get their oil changed after each run...this isn’t just for performance.

Oil breaks down with mileage. I change mine every 5K, easy to remember and track via the odometer.

[Boxtaboy]

I know someone with a 97 Boxster who does oil changes at 15k intervals and has over 150K+ miles on his original engine. I personally stick to a 10K interval, just to be safe. I think 3 or 4k mile intervals for 9 qts of M1 is a bit overkill.

[Brucelee]

Originally Posted by rick3000

Hi,
So I just got back from getting my oil changed, and my mechanic mentioned something very interesting. He told me that Porsche and all these new cars that say to change your oil every 15-20k miles are crazy. He said it doesn't matter what car you have you should change it every 3k miles, 4k at the most. He also said that cars that change the oil at those large intervals are more likely to have an engine failure, he told me about a Cadillac, a Cayenne, and few other cars where the owners did the 15k mile oil change intervals and they all needed engine replacements (the Cayenne at 50k miles).

So do you guys think there is a valid connection between your oil change interval and your likely hood of an engine failure?

-Rick

I have studied this issue for a long time and don't believe there is one answer. I do think your mechanic is half right: 15-20K is insane on any oil save MAYBE Red Line.

On the other hand, 3-4K on a synthetic is a waste of money and MAY result in more wear.

I like 7500 miles on the Box unless one is way into tracking the car. All bets off on that issue for me.

[Paul]

Changing it once a year works for me.