Oil Analysis: 8300 mi, Rotella T6, '90 C4

[porterdog]

Hiyas! Here's a recent oil analysis of the Shell Rotella T6 I'm using in my C4. This oil is available for ~$22/gal at Walmart.

This sample had ~8300 miles on it. My car 'uses' (leaks, mostly) about a quart every 3k miles, and I drive a lot of highway miles. I didn't change the oil or the filter.

Ideally I'd like to pull off 15k change intervals; I took this sample early because I'm taking the car on a 2500 mile road trip next week and wanted to make sure the oil was good. It's holding up well- wear metals are low, plenty of Zn, viscosity is in-spec, and the Total Base Number (reported as Base Number, 5.53) means that there's no danger of acidification. Make-up oil was actually 2.75L.

I don't believe I'll be changing for Brad Penn or Joe Gibbs anytime soon.



ETA: Analysis by Polaris Labs

[db_cooper]

Someone may note the copper is at 24ppm. Not a big number. Porsche used two very long copper oil lines to the front oil cooler (which has copper in it too)

I think that this would raise the copper numbers in the sample. No problems.

Nice zinc number..1290ppm.. Phosphorus..928ppm with a big slug of Magnesium and Calcium. Got a little Moly and Boron too..yumm, tastes great.

13 to 17 cSt@ 100c is the 40w range. 14.2 is just fine for synthetic oil.

Nice report. I use Rotella T6 in my 1986 911 with confidence year round too.

[bkreigsr]

Sodium number looks way low.
Universal averages for 911 aircooled is 86. Mine has been coming back at 280-458 (5 samples) with Brad-Penn.
Also, as mentioned, copper universal average is 8 - have you been tracking your car?
Be nice to know the flash point after 8,300 miles?
Overall, nice numbers for a 133,000+ engine.
Bill K

[porterdog]

Well, sodium is usually part of the oil itself (this virgin analysis shows unused oil w/ 5ppm) so I'm not sure you can really have a 'universal average' unless you account for that in some way. BP probably just uses a lot more of it, hence your higher readings.

No track time, but your Cu number ("copper universal average is 8") should really have both an oil and a mileage number associated with it for validity. Is my run longer than the universal average run? I would like to know that Post up some analyses!

[db_cooper]

Rotella (SOPUS) typically don't use much sodium (salt when blended with potassium) as an additive. Sodium is an alternative to calcium in oil formulations. For some reason I can not explain I prefer calcium used over sodium. I am just prejudiced against salt in an engine for some reason.

[bkreigsr]

Doesn't the sodium serve as an absorbent for the condensation that occurs in the oil tank when the car sits for several weeks/months?

Blackstone bases their universal averages on 4,100 miles.

[larrym]

valuable info - thanks for sharing!

[porterdog]

Sweet- thanks for sharing!

Given this data I think my Cu number is fine. I'll post another at 15k.

[db_cooper]

Doesn't the sodium serve as an absorbent for the condensation that occurs in the oil tank when the car sits for several weeks/months?

By design sodium in engine oil is a detergent. 450ppm would not hold much water. Who wants brine in their engine anyways?

Porterdog is going four to six times longer on his 3.6 UOA than the Blackstone reports on the 3.2 and 3.0 and his oil report looks great..(and the 3.2 and 3.0 reports look great as well) The 3.2 oil sheared down to a thick 40w with a touch of fuel in 1322 miles..the hard track time doesn't seem to bother 911 engines too much.

[bkreigsr]

Originally Posted by db_cooper

....The 3.2 oil sheared down to a thick 40w..

Thanks DB
where did you pull that number from?
Bill K

[dshepp806]

For "entertainment" purposes, next time run your extracted sample, not only through Blackstone, but (simultaneously) through Stavely Labs.

Thanks for sharing!

BEST!

Doyle

[Justin@Athens]

I think that Rotella is largely overlooked by most folks because it is not expensive enough, and doesn't say anything about "racing" on the bottle. With that being said, I will drag up and old thread I started a while back for your viewing pleasure: New Poll: What oil to use.

[db_cooper]

Originally Posted by bkreigsr

Thanks DB
where did you pull that number from?
Bill K

The 3.2 cSt@100c sheared down to 16.11 according to the report.

13 to 17 cSt@ 100c is the 40w range

[M.D. Holloway]

nothing really too scandylus...sodium could come from a few sources including fuel. The concentration is pretty low, seems like Shell has been adding more of it lately.

BTW - "Total Base Number (reported as Base Number, 5.53) means that there's no danger of acidification" in reality that would be a pretty low number and if it was a diesel engine I would be concerned but its a gas engine and the engine is designed to have a TBN of 8 anyway. Acid neutralization is less important in gas engines.

Rotella (to my understanding) doesn't contain any moly - thats not an additive, prolly from the rings.

Also noticed some copper, lead and a wee bit of iron - at first blush I would say its your lower main bearing. I don't see any chrome which is interesting. I thought that engine would have had some chromate in the main...maybe not.

Your oxidation and nitration numbers suggest that you idle more than go flat out.

The oil looks good enough for gubmint work...

oh ya, Stavely is now ALS Tribology. I highly endorse that lab over any other.

[KNS]

Rotella T6 is a great oil and I run it in my daily driver BMW. Becuase it's so bloody hot here in the summer I don't think 5W-40 is quite right for the 911 during that time of the year. Otherwise I'd use it in that car too.

Stavely has made several mistakes on my reports over the years. They keep labeling the wrong type of oil on the write-up even thoughI keep pointing out the error. My last 911 sample with Stavely said I had coolant in the oil.

[db_cooper]

Originally Posted by LubeMaster77

nothing really too scandylus...sodium could come from a few sources including fuel. The concentration is pretty low, seems like Shell has been adding more of it lately.

BTW - "Total Base Number (reported as Base Number, 5.53) means that there's no danger of acidification" in reality that would be a pretty low number and if it was a diesel engine I would be concerned but its a gas engine and the engine is designed to have a TBN of 8 anyway. Acid neutralization is less important in gas engines.

Rotella (to my understanding) doesn't contain any moly - thats not an additive, prolly from the rings.

Also noticed some copper, lead and a wee bit of iron - at first blush I would say its your lower main bearing. I don't see any chrome which is interesting. I thought that engine would have had some chromate in the main...maybe not.

Your oxidation and nitration numbers suggest that you idle more than go flat out.

The oil looks good enough for gubmint work...

oh ya, Stavely is now ALS Tribology. I highly endorse that lab over any other.

Rotella has a small dose of Moly. 10ppm iron is very slight..911 cam chains and sprockets throw off most of that, like some other air cooled motorcycle engines. The lead ppm numbers are very small..almost like background scatter, except the 24ppm copper..which probably is coming from the oil cooler and copper plumbing.

Here is a virgin oil analysis of Rotella T6. 62ppm of Moly.

[dshepp806]

I experienced the opposite with Blackstone,..spent a lot of dollars to verify MUCHO comparisons to Stavely on the same sample(s).

Anywaze,...just saying "just be sure your data is dead-on"...

BEST!

Doyle

[RSTarga]

15k is too long between oil changes. I do it 4 times year no matter the mileage.

[bkreigsr]

Originally Posted by db_cooper

The 3.2 cSt@100c sheared down to 16.11 according to the report.....13 to 17 cSt@ 100c is the 40w range....

thanks again
so why do we bother to buy a multi-grade oil if it is going to shear down to a single grade after a certain amount of track useage? media hype?
Bill K

[porterdog]

Originally Posted by RSTarga

15k is too long between oil changes. I do it 4 times year no matter the mileage.

It's your money; you can do whatever you want with it. (My mom taught me not to waste mine.) If the oil is in-grade, not contaminated, not acidic, and the wear metals aren't extreme there's no reason to change it.

@dshepp: The analysis in the OP was by Polaris; those Blackstone reports were included for color.

Regarding shearing, the reported viscosity is at 100C; the multi-rating involves checking at other temperatures as well, but generally we're concerned with operating temperature.

So far as I understand the Base Number, values down to 1 are permissible as they indicate a continued ability to fight acidification.