There have been a lot of threads on oil change intervals. I was planning on sticking to a 5,000 mile interval. I do a 16 - 20 mile each way romp to work, so it's mostly highway miles. Was working late nights and weekends, and missed my 5,000 mile interval.

Ended up climbing under the car to do the change at 7,000 miles. I sent in my oil to Blackstone to get the analysis. Was nervous about what they would find. Here's what the text said on the test.

I'm not telling everyone that they should go 7,000 miles between changes in their cars, but I did, with good results. I am not a "alte kacker" kind of driver. I do have some fun pushing it to red line, and have had some occasional instances where I was watching the road and not the tach (why would I do that?) and I passed redline by a few hundred. Need to have my limiter checked out.

For those of you who think that I'm crazy, I ask this question, "why do we get the oil analysis done, if we aren't going to operate our cars based on the results that we find?" I will probably go to 7K on my next change as well. Not sure that I really want to push it beyond that, but I'm not seeing any issues at the 7,000 change.

Recently I have run a few autoX. Wondering if that will alter the results at the next change?

larry

 

I've gone 7000 miles between oil changes several times.

(P.S. Stand by for the forum fire storm...)

 

Larry, when did you switch to Mobil 5W50? Based on your UOA, I'd say you changed to the 5W50 on your June 2011 change because your Sept. report shows a nice improvement in your SUS viscosity (210). I think this is why you are seeing inproved results. One on the great reasons to do UOA's on a regular basis.

Your copper is still very high. Your engine is still breaking in. You should still do 5,000 miles changes until your copper drops more, IMO. The only wear metal that has improved in your report is iron. My copper (7) is a fraction of yours (33) for similar mileage. Even my 993 Turbo has lower copper (4) with 5,000 mile changes (V-Twin 20W50) after 58,000 miles.

Here is my report (from the Boxster) using the same 5W50 oil. The first few oil changes were Red Line 5W40. The Mobil 5W50 has proven a little better oil, plus my shorter run intervals (since I still need to drive the Turbo every other weekend):

 

Larry, Using data to support your actions is always better than being a lemming and following advice blindly. I also do not follow the 5,000 mile once a year mantra....because thats what others do. Also you might want to black out personal info on your pdf...

NO...what makes you think 33 ppm is too high for Cu? here is an article I found for diesel engines, but the ideas are sound:

Copper

 

Well, when mine are a fraction (4 and 7) of Larry's (33) and even his Universal Average (18) is about half. That's all. High copper could be bearing wear.

Larry needs to ask, "Why is iron dropping like a rock (good) but not copper (might not be good)?".

 

The problem with the data as you look at is you are making comparisons without understanding the standard error (or measurement error for that matter). In reports I have read there is a huge standard deviation associated with Cu in oil samples...so there is little significance to the difference of say 18 and 33 (or 7 for that matter).

 

OK, I neither agree or disagree with you. I don't know (or have enough info) to go either way.

But, how come our respective reports all have a relative tight range? If there was that much error and deviation, wouldn't we see it in our own reports, too?

 

You do or don't agree with what...how to compare data points?

All reports...I see one with a 33 value and your reported numbers. That makes three data points. Please define "tight range". Try getting a realistic sample size. From some of the reports I have seen posted the standard deviation is 50+ which would mean all of the data points posted are in the same population.

 

It is up the individual how often he changes his engine's oil.

I use 5K miles based on my research and where I live, how I drive my cars.

Do a UOA in the winter. I think you'll find the water content up. 16 to 20 miles may not have the engine warmed up that much even on mild days. In the winter the engine may not get very warm at all and the result in over time water builds up in the oil.

It was after the results of a UOA done in the dead of a mid-western winter that found around 7% water content in the oil of my new Boxster's engine.

Seven percent is roughly about 0.6 of a quart of water. It was this unexpectedly high level of water that prompted me to monitor coolant temp and this was when I found my 10 or 12 mile drive on back roads from home to work wasn't getting the engine hot at all.

Even 75mph blasts down the freeway for around 70 miles (each way) when I drove down to visit my folks never got the engine that warm.

For my usage, my driving, 5K miles has the oil changed *before* it shows signs of being degraded.

My point and I have made it a number of times is I prefer to change the oil a bit before it needs to be changed, not after.

Now once in a while I'll change the oil in my car and then head out on a road trip covering nearly 5K miles in one week. Back home I'll do an oil change and the oil comes out not completely black. The oil might have been good, easy, for another 1K to 2K miles, maybe more.

But the problem is those additional miles are not going to be racked up driving 8 or 10 or more hours per day at speed for the next few days, but racked up driving in stop/go city traffic, with lots of idling, some highway miles, and unfortunately some short trips.

The oil can go from still good to being ready to change way before another 2K or so miles have been accumulated.

Also, there are other owners who subject their cars to harsher driving conditions and 5K miles might be pushing the envelope.

For others 10K miles might be ok.

But most owners I believe based on what I read are in the camp that their engines would be better served having the oil changed at 5K miles vs. more miles.

For me following a 5K miles oil change interval is easy. I need no windshield sticker pasted up at the top of the windshield to remind me when the next oil change is due. Every 5K miles ... oil change time.

For instance, I had the oil changed in the Boxster at 255K miles. At 260K miles it will be due again.

The Turbo is in getting its oil changed today with just over 95K miles on its odometer. At 100K miles I'll have it in again for this service.

Sincerely,

Macster.

 

never expected to learn how to spell "alte kacker" in here. not many alte cacker's drive porsche turbo's. ha.

 

I just put 5000 miles on my car since July 4 averaging over 65 mph according to the GPS. Do I need an oil change already? I typically change my Boxsters once a year or 10,000 miles.