Just did the second oil change since owning my XK8. I've become a big believer in doing an oil analysis every now and again, especially on cars I just bought. This one was no exception. I sent a sample of the oil that was in the car when I bought it to Blackstone labs for an analysis (at 69k). I had no idea when the oil was last changed. The results came back more or less normal, with a slightly higher instance of silica (sand) in the engine, but nothing to get worked up about.

I put in 5W30 Mobil 1 and a Wix filter, ran it for just under 7k miles, changing it out just a couple of weeks ago. I sent another sample to Blackstone for analysis (yes, I am really that **** retentive).

Surprisingly, the results just came back with an even higher indication of silica in the oil, so much that the lab called to ask if I recently had any work done to the motor (suggesting a mechanic might have got some dirt into the engine or some such). The only work I had done was the timing chain tensioners replaced at the Jag dealer, and the plugs which I did myself. I run a stock filter; both it and the intake tube were clean inside and out and in good overall condition. I cannot figure out where the extra sand is coming into the engine. There was also a slightly higher instance of metals indicated, but nothing major according to the tech with whom I spoke.

A buddy suggested it might be from an 'unclean catch' (a dirty oil pan or other matter that corrupted the sample), but I was pretty careful to avoid this. I was thinking it could it be from the synthetic oil working loose dirt and sludge that was left idle by ordinary oil. This was one theory I heard, but I'm not sure how plausible it is. I am thinking of sending another sample in sooner (3k miles) just to see what happens to the silica levels. This oil sampling can be addictive....

A penny for your thoughts.

 

oh yah, keep us updated on the next oil change!

 

Replacing Timing chain tensioners is fairly significant and dirty. The cam covers need to come off, exposing cams, chains, and everything in the front cover. Any dirt introduced here will end up in the oil pan.

Dan

 

Interesting test and I think those results vary in engines .I mean you might not get exact results at any other engines .
Can this appy to a V12 engine with same results ? That's what I would like to know

 

Not to hijack this thread, but a big welcome to Texas Dan! Dan has extensive knowledge of these Jags and is very giving of his time and expertise in helping others. In short, a GREAT new member!
Best regards,
Brian

 

From past threads, it's probably not a surprise I'm a firm believer in oil analysis, especially to govern oil change interval. I'm glad you chose to do this and if you keep going I am interested to see how future samples come out after you stablize the engine. Could you also post the recommended interval on future reports?

Thanks

 

What did the oil analysis have to say about the useful life of the oil?

I had my oil tested only once and the report was unremarkable except to indicate that full synthetic would run 15k miles with full protection intact.

 

How much does the analysis cost, and where do you send it? Do they have a website?

 

Blackstone Labs is one, about $20.

 

@BurgXK8

Can you post your results? or at least mention the amount measured?

 

I'd think that it really isn't much silica/sand in the oil to cause a bump in the analysis, and as MrTexasDan says, doing the tensioners could be significant enough to introduce contamination. I'd lean that way and then maybe do another analysis and see where that one gets ya.

 

Sorry for the delay. I would rather not post the full pdf from Blackstone as it has personal info all over it, but I can tell you this much from the readings (the numbers mean parts per million):

Iron: went from 5 in the last report to 29; universal average is 8.

Lead: went from 5 to 15; average is 5.

Molybendum: went from 7 to 112; average is 53

Silica: went from 17 to 203; average is 12.

There were other readings also, but these were the ones that stood out.

You can see that the silica reading was the most outrageous, but even at this level the Blackstone lab tech said it wasn't a major cause for concern, just something to keep an eye on.
There was still lots of life left in the Mobil 1, with a TBN reading of 3.2 (scale of 1-7). So 7k miles is probably not too much for an oil change interval, but a mid-change filter swap might be a good idea since there are contaminants floating around, regardless of whether or not the oil is still good.

I will be changing it all again sooner than last time and will post the new results when I do a re-test. In case anyone is interested, oil analysis costs about $20, with an additional $10 if you want the TBN number, which is not needed once you figure out what a good interval for your oil change is. I like to do it once or twice with a recently purchased car, or if I swap oil types for whatever reason to see if they hold up over time.

http://www.blackstone-labs.com/

 

The Silica readings are indeed very high, not something you want for a long period when it is of the abrasive sort. Here is some more info on the topic:
http://www.machinerylubrication.com/...t-oil-analysis

Not sure if BSL was able to determine what source could have contributed to the high silica reading (i.e. dirt/sealant), but considering the job that has been performed it could even be combined by small air leaks (filter not fitted right, oil dipstick tube not fitted right) or so, but these can be checked. I have no experience with dirt that could drop into the engine during a job like that (in terms of silica readings). Sealant would definitely be a source as you need to apply this on certain spots when putting the front cover and valve covers on (maybe they spilled somewhat?). FE is somewhat higher from what I have seen on our engines, but not that much, so the high Si readings aren’t hurting your engine for now.

What where your aluminum and copper readings?

Would indeed keep a close eye on this, but so far not something to have sleepless nights imho.

 

Copper: 4/4/3
Aluminum: 3/3/3

Both are pretty much normal.


And yeah, the guy from Blackstone suggested the high silica readings could have been from sealant or other gasket material making its way into the engine from the recent work on the secondary timing chain tensioners. Will check next time, and if it's the same level I'll be a monkey's uncle - no idea where the sand would be coming in....

 

Boy, whoever did the secondary tensioners hopefully didn't use gasket sealer on the cam cover seals. Not only is this not necessary, but can actually screw up a perfectly good cam cover seal set. Properly installed, they do not leak dry.

BTW - I regularly do interim filter only changes between my 12K change intervals that came as a result of a couple oil analyses from Blackstone...No, I'm not trying to open up the debate again, just stating what I do.

 

@BurgXK8
Looks indeed good!

@Stevetech
JTIS: "Apply RTV sealant WSS-M4G320-A3 to two places on the joint between the timing cover and the cylinder head.The application of sealant must be 3mm diameter by 12mm long. Install the cam cover immediately after applying the sealant.The cover should be installed directly to the head without smearing the sealant."

Am not always following JTIS, but for this one I am also using sealant on these 2 spots, as I can see how this could leak there.

 

Not necessary

 

The joint between the front cover and head is not perfect. I measured up to a .0005" "step" across this surface on mine. I assume this is why the RTV is specified ... to prevent a seepage path. I can imagine that the cam cover o-rings may not seal across this step without some help.

In practice, I don't know if it's really needed, but why find out?

Dan

 

I've done dozens of these cam cover seals in my business on customer's cars. In the last 5 years, I'll bet I've done 50. I never use sealant on the part lines. Returns are at my cost. One return and I would be putting sealant on every time.

If I have the front cover off however, and the original factory sealant is removed out of the part line, that is a different story. But, a straight cam cover seal replacement where the original factory sealant fills any voids, I do not disturb. Torqueing the cam cover bolts properly is far more important for effective sealing than trying to make up for bad shop practices by using sealant (all over the entire neoprene seal)....and I've had to clean up a few of those leakers from DIY attempts.

 

And don't over tighten!