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Old 10-05-2005, 11:03 PM   #1
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Oil Change!

My mechanic told me I should have oil change every 3,000 miles, but the Manual said we should have oil change every 15,000 miles. Which one is correct?

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Old 10-05-2005, 11:25 PM   #2
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The manual is correct, however I would not wait for 15,000 miles. I would change the oil at about 8k-9k mile increments. If you dont happen to put that many miles on your car in a year a yearly oil change is recomended.
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Old 10-05-2005, 11:30 PM   #3
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Thanks! I guess I will just change oil once a year coz I don't think I will drive my box more than 10k miles a year.
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Old 10-06-2005, 06:33 AM   #4
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Some Discussion Please on Oil Changes

For those of you who use your cars as daily drivers:

How many of you change your oil every 7500 miles and how many wait to change it at 15K?

Iím due for a 7500 Oil Change- but my car is running so well Iím half afraid the dealer will screw something up.

Before the Boxster- I always chagned my Oil at 3months/3000 miles-- even thought the manual stated 5K changes in my previous wheels.

Thanks for the advice.
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Old 10-06-2005, 06:34 AM   #5
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Was just discussing oil changes, etc. with one of our local Porsche shop (not dealer) mechanics, who I find very trustworthy. He noted that he finds it common to check Boxsters at the 7,500-10,000 mark and see very dirty oil/filters. I know that oil is expensive and the book says 15,000, but I plan to keep an close eye on the dipstick. There is no better medicine to keep an engine healthy than good oil. I stay with Mobil synthetic as Porshe recommends.
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Old 10-06-2005, 07:28 AM   #6
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More on Oil

The tech in the Porsche magazine Excellence a couple of months back noted that 15K changes are probably too long for US driving conditions. So, Iím leaning towards changing it soon.

In response to limoncello:

Can I simply use the dipstick to evaluate the color of the oil, or is that an inaccurate method?

Thanks.
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Old 10-06-2005, 07:30 AM   #7
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Quote:
Originally Posted by 97Boxsterian
My mechanic told me I should have oil change every 3,000 miles, but the Manual said we should have oil change every 15,000 miles. Which one is correct?
Are you using a "Porsche specialist" mechanic? If so, find a new one because he should know better.

Ours is changed between 10K and 15K miles. My wife tells me when it hits 10K and I change it when I get the chance, usually within a month or two, but we put 2K miles/month on the Boxster so it's never past 15K. With any car you should follow the manual, not what the guy who gets the bucks from the extra oil changes wants.

Oil break down is mostly affected by how often you drive it, the climate, engine load and the filter. The less you drive, the faster (mileage wise) the oil and filter break down due to condensation in the system. The "dirty" oil or dark color is not from dirt in the oil, it is from the heat changing the color over time. The viscosity is what you have to worry about and it does not break down with Mobil1 for over 15K miles if the car is regularly driven. If it is driven once every week or two, you should change it every year. If it is driven less than every two weeks, you should change it every 6 months. If you drive in stop-and-go traffic a lot, you should follow the shorter schedule listed in the manual. You should only use a fully synthetic, 15K mile oil and original Porsche or OEM Mahle filters.

Before you think about using the 15K mile Mobil1 oil in your other cars to lengthen your oil change cycles, here's the problem with that. Oil filters are made to the auto manufacturer's specs. If the manufacturer says change the oil every 7500 miles, then the oil filter is made to last that long. Unless you can get a Mobil1 oil filter that will last 15K miles like the oil, you should stick to the manufacturer's recommendation.

As an aside, Consumer reports did a test a few of years ago to see if the every 3K oil change helped protect engines better. They took two each of several different automobiles with different size engines. One of each model had the oil changed every 3K miles and the other one had it changed according to the manual specifications. After 100K miles, they disassembled the engines and inspected them thoroughly. The verdict was no difference in wear, even microscopic, at all between the every 3K oil change engines and the manual spec change engines.

Have a great day!
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Old 10-06-2005, 09:12 AM   #8
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Quote:
Originally Posted by deliriousga
Ours is changed between 10K and 15K miles. My wife tells me when it hits 10K and I change it when I get the chance, usually within a month or two, but we put 2K miles/month on the Boxster so it's never past 15K. With any car you should follow the manual, not what the guy who gets the bucks from the extra oil changes wants....

Hi, I agree with you to a point. You should follow the Manual, but you need to understand what the Manual is saying. The Oil Change Interval spec'd in the Manual assumes Ideal Driving conditions, which almost no car experiences. Ideal Driving conditions assume that; a.) Each time you drive the Car, you are driving 10 or more miles, b.) that you do not encounter Stop & Go situations, or periods of idle, c.) that your Fuel is Ideal - with the proper Octane Booster (some can contaminate the Oil sooner than others), d.) That your Plugs are ideal - READ: relatively New, e.) that your Air Filter is ideal READ: relatively NEW finally, f.) that you do not encounter any dusty conditions while driving. And it assumes all these conditions for the entire Service Life of the Oil.

Most Manuals also include a Caveat that the Service Interval should be shortened if Severe driving conditions are met. There is great ambiguity about the Ideal and Severe conditions mentioned.

But, every Dealer or Mechanic (who had any knowledge of cars at all) I have ever spoken to has said that Ideal driving conditions are really never encountered, and therefore the Change Interval s/b shortened. In my experience, using MB1, 10K mi. is about right for any N/A car. A Car w/ Forced Induction should place the Change Interval closer to 7,500 mi.


...As an aside, Consumer reports did a test a few of years ago to see if the every 3K oil change helped protect engines better. They took two each of several different automobiles with different size engines. One of each model had the oil changed every 3K miles and the other one had it changed according to the manual specifications. After 100K miles, they disassembled the engines and inspected them thoroughly. The verdict was no difference in wear, even microscopic, at all between the every 3K oil change engines and the manual spec change engines...
Again, I have some conflicting reports, scientifically conducted, which state that there is an issue in changing the Oil religiously at the 3k mi. Interval.

In this Study, Oil samples were diagnosed in a respected Laboratory and checked for, among other things, the metal content of the Oil at different, specific, mileages, rather than disassemble and 'mic' the engine components as in the CR test.

This Study discovered a couple of surprising results. The biggest was that frequent Oil Changes actually increase wear to the engine as noted by the increase in metal content of the Oil in the 1st 3k mi. after new Oil was installed. This is counter-intuitive, but this was experienced consistently with the new Oil. The reason is most likely that when Fresh, the Oil isn't actually operating at it's peak due to a full mix of Anti-Oxidants and Detergents. With age, these wane and the Oil actually does a better job of lubricating and flowing. I'd be happy to post a link to the Study if anyone is interested.

Happy Motoring!...Jim'99
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Old 10-06-2005, 09:52 AM   #9
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Quote:
Originally Posted by MNBoxster
I'd be happy to post a link to the Study if anyone is interested.

Happy Motoring!...Jim'99
Please do. That's very interesting.
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Old 10-06-2005, 10:04 AM   #10
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So changing you oil to early can result in harm to your engine not letting the oil "break in"?
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Old 10-06-2005, 10:04 AM   #11
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I watch the dipstick regulary, it's one of the ways I communicate with the car. It tells me level changes and color. Whether from heat or dirt, very dark-to-black is not a good thing in my "old system" mind.
Related question for the forum: do track miles differ from regular miles? I would think they do. The rpm's are higher, but my temp gage stays not much above 180 on the track, even on a hot summer day in the south.

Too much knowledge - my instincts tell me to change the oil more often due to occassional track use - every 7,500 feels right to me. But now I need to worry about my oil being "too fresh"???
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Old 10-06-2005, 10:49 AM   #12
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Quote:
Originally Posted by limoncello
Related question for the forum: do track miles differ from regular miles? I would think they do. The rpm's are higher, but my temp gage stays not much above 180 on the track, even on a hot summer day in the south.
Tracking it should put you on the higher, more frequent maintenance schedule for everything. Even though the water temp does not go up, your rpms are heating the cylinders to higher temps (go radiator ) so the oil does break down faster under that much stress. Same with the brake fluid, more stress & heat so more frequent changing is necessary.

Two factors for maintenance. First, follow the science and not the emotion (easier said than done). Second, as with everything in life, follow the money to find out who's best interest is at heart.

Btw, let me know the next time you're tracking it. I'd love to come out and watch.

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Last edited by deliriousga; 10-06-2005 at 10:55 AM.
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