vtrich

So, the car is burning more than a quart every 1000 miles,...more like a quart every 600 - 700 miles. Has 84,000 miles and I put around 3000 on it each summer. I didn't change the oil last spring,...kinda lazy and I figured I'd been adding so much,...well,... Anyway, I did change it this spring,...couple weeks ago,..but before I did, I took a sample and sent it off to Blackstone labs to see what they thought.

I kinda figure I'm due for a top end,...with the oil useage and even though I'm pretty sure the valves are adjusted properly they're still kinda noisy.

OK,...so,..the oil analysis came back really good. I guess I figured the oil would be all mucked up with all sorts of stuff,...but apparently not.

Finally, the question, would you expect to see all sorts of extra stuff in the oil if you need new guides? I suppose the report is telling me that the engine is not eating itself up,...but is there anything else I'm supposed to be learning from this report?

THANKS for any insights!

Rich

race911

Not really. You're just seeing with a ~25 year old car what we started seeing in the business when the typically driven 3.2s got to be 5-6 years old. Was frustrating to drop a (then) $2500 bill on a guy with what I called a near-new 911 that had supposedly been perfected...........

dshepp806

Good question,..as the oil samples provide metal content (all of 'em)....representative of the engine area breakdowns....this would be in the extreme,..still informative.........

Otherwise,..TBN is important, over time....My intial runs with Staveley showed me TBN drops over time,...most (in the know) ensure that the oil change happens before 50% TBN...one would have to spend some $$ and time to garner "where/when" that happens...aside,..every 3K for me (oil changeout),..religiously (or, should I say "zealously"?) ,..and the forementioned doesn;t (then, really) matter. Big thing is the trend" on the numbers,..and one would have to provide long term standing data on such a curve,.....I sample my oil at every changeout....I look at PPMs on Z&P (over time), as well.

BEST!

Doyle

Steve Weiner-Rennsport Systems

One thing to remember with engines that consume oil is that their octane requirements really go up since the oil in the combustion chamber lowers the effective octane of the fuel being burned. The octane rating of oil is pretty darned low.

This means that the thresholds of detonation are significantly reduced which makes finding broken rings much more prevalent. Piston & chamber deposits certainly add to the problem, too.

Given the piston damage that occurs when this happens, I usually recommend no delays in getting the top-end reconditioned before one needs to buy more parts than normal.

At 600-700 miles per quart, you are ready.

500

The other thing I would add is that the oil that leaks down the guides is either burned in the combustion chamber or dragged straight out the exhuast, it is not recirculated so there is not as much chance for wear deposits to accumulate in the oil as there is with, say, main bearing wear.

In addition to the damage Steve noted, the valves and seats will start to accumulate damage due to excessive play.

theiceman

isnt there also the possiibilty that the valves have worn significantly enough that they will wear no more ? .. now you are just letting oil through . if this was the case you would not find any particulate guide material in your oil ... well .... eventually as Steve states you will find a ring

vtrich

THANKS all for the replies. I suppose this is all good news,...I mean as Steve said,...I'm due,...and I was assuming that. But since I don't have much in the way of metal particulates in the oil,...it seems everything else should be in pretty good shape. Always the optimist.

theiceman

yeah should be cheap to fix ..