Oil Change = Engine Failure ???
 

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 :cheers:

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.

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.

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.

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.

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"

:cheers:

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! :D
Seems like it would be good for the oil industry though..

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.

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.

:cheers:

It is interesting to see everyone's views on this, I am starting to think I should do the oil change every 5k miles, instead of 7500k miles.

Although, if you take ideal conditions of 60mph over 5,000 miles, that's 100 hours. So everyone start changing your oil every after every 100 hours of use. :rolleyes:

Rick3000, what did you really expect your mechanic to tell you? Business is slow. He's just trying to make a living.

We've done the used oil analysis and 7500 mi is pretty much tops for a drain interval for street driving. By 10,000 mi, the oil was crap quite a few miles before that point. 5000 mi is honestly a very good point to change the oil. Sooner may be overkill, but certainly can't hurt. Take it from someone who has seen many intermediate shafts with long drain intervals and the kind of crap that fills the IMS tube (and not to mention what the bearing looks like) once the seal stops sealing (happens pretty quick once there is even the slightest play in the bearing).

I wouldn't put too much importance
 

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.

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. :cheers:

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:)

Gauge his remarks by his age as well. If your mechanic is a 55+ year old guy, he is still speaking out of his fossil fuel oil paradigm.

Mechanics are a lot like farmers. Very slow to change and accept new ways of accomplishing the same thing, even if it's faster, cheaper, and more reliable. The old ways are known and trusted because of the test of time.

I'm this way about motor oil myself. I run M1 and still treat it like fossil based oil and change my oil and filter every 5000 miles or 1 year, whichever comes first in all my cars. 2 of the 3 use synthetic oil.

What the other poster said is so true... oil is by far cheaper than a motor, and your mechanic thinks the same thing for a reason. He's replaced motors that didn't need to be replaced if the owner had just changed the oil more frequently.

I understand my mechanic has a personal agenda, it is benificial to him when I spend $150 every 3k miles for an oil change. Thanks for all the advice!

Now I'm curious what oil change interval people who have had engines failures used?

Wouldn't it be in Porsche's best interest(and the oil companies) to lower the mileage between oil change intervals if the oil is toast by 10,000 miles? Also, since the flat 6 holds about double the oil of a standard passenger car engine, I would assume that would allow for longer intervals?

Adam - a large quantity of lubricant can be be worse off than a small quantity. Do you know what 9+ litres of oil looks like after 10,000 miles of short / slow trips in a Northern hemisphere climate !! The oil is not nice to see, smell, touch or be part of a very expensive piece of equipment like an engine. That amount of oil takes about 10 miles to fully come up to temperature and burn off the accumulated acids and water vapour, while your average car's oil is up to temp at less than 5 miles.
Not many people have mentioned it, but I feel the car feels quicker after an oil change.......

Mine feels the fastest after a wash & wax! ;)