Oil Change = Engine Failure ???

[jmatta]

Steve, your point is very well taken. Those that drive their cars around town, on short trips and errands, should definately change their oil every 3-4k miles. As you pointed out, the oil never gets hot enough to burn off the crud. I avoid driving my car unless I know I will get it good and hot, but still change the oil no longer than 3k miles (once a year for me).

I've also added the LN oil filter adapter and magnetic drain plug to my car to catch the fine particles the standard filter misses. I'm really curious to see what the drain plug looks like next time I change oil; hope there aren't a bunch of filings attached!

[spine911]

Originally Posted by cnavarro

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).

Personally, i'd take this guy's opinion. An oil analysis is the best objective way to scientifically measure the oil's performance. I also go with 7500k oil change intervals just to be safe.

[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.

[geoff]

Originally Posted by Adam

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?

I talked to a mechanic at the dealer shortly after I bought my '01 Boxster way back when it was still under warranty. He said the main driver for longer oil change intervals was government pressure on car manufacturer's to reduce the amount of oil that had to be disposed of. All the service writers at my dealer say the Porsche recommendations are fine, cars burn cleaner each model year, and actually turned my friend away several weeks ago and told him to wait another year before changing his oil because he didn't drive the car enough to justify the expense.

If you look at the Porsche recommended service interval today (see http://www.porsche.com/filestore.aspx/default.pdf?pool=usa&type=download&id=maintenanceintervalsforporschevehicles&lang=none&filetype=default ), Porsche has very quietly changed the oil change interval for my '01 Boxster from 15K miles originally down to every 12K miles. I have been changing the oil every 7,500 miles on both my Boxster and '05 Carrera (with Porsche saying every 20K miles for the '05 model year) and am thinking about following MarcW's example for over 200K miles and changing to an every-5K-mil oil change interval.

If you look at the Mobil1 web site, the "extended performance" Mobil1 oils say "Guaranteed performance and protection for up to 15,000 miles", and the 0W40 used in our cars aren't listed as extended performance. The Mobil1 FAQ just says "Mobil 1 with SuperSyn Technology exceeds the latest industry and OEM requirements. It is designed for vehicles under warranty and will provide protection for the maximum oil change interval recommended in your owner's manual or by your oil life sensor" Lots of disturbing ways to interpret that statement1