james944

Hi Guys,

Don't tase me for bringing oil up again, but the brief resurgence of the "Anything New On The Mobil 1 Front?" thread has made my next oil chance an angst filled task. I think most people are at last a little uncertain about which oil they want, and worse everyone who's been following the oil threads is really frustrated by the lack of consensus.

I'm starting to think that the best way around this confusion may be a comparison of used oil analysis results. I know that at least a few of you have your used oil inspected for abnormal signs of engine wear. I bet that if we share all this data we will have a big enough sample to get a handle on which formulations are protecting stressed engine components, and which oils are contributing to premature wear.

I'd particularly like to hear about results from 964 engines running Castrol (GTX 20w50 (what the PO put in the car) or GTX High Mileage 20w50) ) or Mobil1 products (0w40 - TSB 1701 didn't have to apply to all models since '84 and 15w50), but info on any oils that produce good or bad UOA results would be helpful.

Thanks,
James

james944

As a start I've found this page:
http://members.rennlist.com/oil/test_results.htm
but the data set is too hard to manage and there are too few 964s to get any clear answers.

Frighteningly it looks like most oils have produced their share of bad results.

ilko

I just sent a sample of GTX 20W-50 to Blackstone Labs. Should have the analysis in the next couple of days. Regarding the link above with test results, I find them a little dubious, at best. If those results are all correct, we would be getting engine rebuilds on an annual basis.

TR6

I also just sent in a sample to Blackstone but haven't gotten the results yet.

The problem with this (comparing oil samples) is that it's not apples to apples. You are interested in the wear differences between the different oils to determine which oil protects the engine best. But there is such a wide range of variance in engine wear based on other factors such as engine condition, mileage on engine, miles on oil sample (one guy changes his oil at 1000 miles and another changes his at 5,000 miles), useage (track or street), etc of the engines themselves regardless of what oil you use. In other words, I wouldn't expect an engine with 100K+ miles that sees track/DE useage to show the same wear levels as an engine that has 40K miles and only gets street use even if both were running the same kind of oil. So if you see an engine showing higher wear indicators than another engine, you are going to draw the possibly erroneous conclusion that the wear is because of the oil when it may not be the oil at all. Maybe I'm misunderstanding what you are proposing.

It would still be interesting to see sample results from other 964's and I'm happy to share mine.

bgiere

It is a fun comparison, but probably worthless to compare cars UOA's with each other...Need to get consistent,long term trends in order to have useful comparisons. Too many variables involved.

pat056

I'm glad to see this thread! At least you guys are attempting to get at a root problem and determine an analysis technique.
Thanks for the refreshing change.
I'm getting ready to change my Mobile 0w40 on the 996 and Mobile 15w50 out of the 964 that only sees the track. Where do I send it and how much do they need?

TR6

http://www.blackstone-labs.com/
From their site:

Run the engine before you take the sample to get the oil at operating temperature (driving about 20 minutes should do it). Getting the oil up to operating temperature should help cook out any normal moisture or fuel build-up.


If you're taking your sample while changing the oil, let some oil drain before you fill up the bottle. Try not to get either the first or the last oil out of the pan.

If you can't access the pan and need to use a pump, thread the tube down the dipstick and pump a sample up into the sampling bottle.

We need 3-4 oz to complete all our tests. But even if you only have 1 oz, we can still do at least two, if not three, of our tests. If you have questions about whether we'll be able to work with your sample, call us.

Complete the oil sample information slip.

For the Unit Number field, please identify what you'd like to call this engine (e.g., Truck 1, Old Blue, 91 Jimmy).

For the Make-Up Oil field, please put the number of quarts added between oil changes.

Do you want a TBN? This is a test used to measure the amount of active additive left in the oil. It may be useful if you are interested in extending your oil usage. The test costs an extra $10.

Place the oil sample bottle in the plastic bag. Put the sample, information slip, and a check or credit card number in the black mailer tube and send it to us.
Some post offices mistake oil samples for hazardous material. Oil is not hazardous material. Blackstone Laboratories' oil sample kit meets all postal requirements. To see a letter you can give the post office to help reassure them, please click here.

james944

Thanks for the interest guys, I can't wait to see your results.

I agree that factors other than oil will cause big differences in engine wear rates and thus in UOA results. What I hope to see is that these other factors exert far greater influence on engine wear rates than oil choices does. That constantly lugging your engine and never changing your oil is much much worse than making the wrong choice between Mobil1 15w50 and Castrol 20w50. If this is the case than we can probably conclude that we're all too worked up about this oil issue. Conversely, if everyone who uses 0w40 as motor oil reports that their engines disintegrate in 10 miles we might want to reconsider using it next time.


Even better, if we can get a big enough UOA data set together along with accurate information on engine health, running conditions, etc... we could use statistics to figure out which combination of factors contribute to the greatest variation in engine wear. Aside from the pure nerd factor, that might really help us get an idea of what causes engine wear and how to best treat our cars.

Thanks again,
I hope all your UOAs come back normal...

C4Russ

Good timing. I just got back my results from Blackstone. 91 C4, 128K, 7,500 miles on Mobil 1 (I know, an experiement.) The viscosity was solid and all metals are in the normal range sans iron. Iron tracks with milage so I had a somewhat elevated iron reading.

I was worried about engine wear at my milage. I read so often about people rebuilding these motors at milage that is 1/2 of mine and I sometimes wonder if I'm driving a time bomb. From my results, I'll keep driving this for quite some time as my leakdown and compression numbers are good.

I sometimes wonder if these engines are rebuilt without cause? Is it that some of us just want a rebuilt engine?

TR6

Russ, does your car see track use or 100% street?

If leakdown and compression are good and the oil analysis isn't showing a bunch of bearing metals floating around, I'd drive it indefinitely til I had some indication not to. I agree with you that in most cases, you can continue to drive a high mileage, even partially worn out engine for a much longer period provided one don't push it hard for extended periods (track). Cars that see a lot of track use will show wear in the oil analysis much quicker than street cars. And in my case, I reached a point where I had no choice but to rebuild because mine spun a rod bearing which increased the cost of the rebuild. Waited a bit too long in my case...

MisterRisky

I think that what TR6 mentions here is part of why some get a rebuild as soon as it might be needed. If you are really risk averse it makes some sense to go ahead and spend $8K now so as to hopefully avoid spending $12K later.

pat056

So with all the talk about the evils of not making the correct oil choice . Where does this show up on the oil analysis?

C4Russ

It's all street. I don't track at all and I'd say that if I were racing, I'd have a different viewpoint. I typically drive this car daily, rain or shine. If I head across the state, I'll take the Porsche.

Everything looks solid and the oil report is good. My only regret is not having done the oil reports sooner. It would be nice to have the history. I like the Blackstone reports in that they show subsequent results on the same page. Pretty easy for me to know if I should at least ask some questions. No doubt about it, when one has an engine which has such high rebuild costs, knowing what's going on in there is comforting.

james944

Hey Russ,
Just to clarify, were you running 15w50, or 0w40.

Either way, glad your results came normal.

ilko

I got my report but was in Chicago earlier this week sorry for the delay. As you can see iron and lead are high, everything else is normal... I did add a small amount of GE EOS to the oil, which might explain the higher zinc average.