Oil Test results interpretation - PeachParts Mercedes-Benz Forum

fj bertrand · #1 01-06-2004, 06:30 PM

Hello All. Just received results back from a engine oil sample on my 1991 350sdl

The oil is Shell Rotella 15w40.

Everything is normal except that potassium is at 30 ppm.

test results:

wear metals: Iron 53, chromium 8, lead 4, copper 4, tin 2, alum 4, Nickel 10, silver 6. Boron 286, Na 6, (additives: Mg 25, Ca 2721, P1379, Zn 1435 and Mb 2) Physical analysis: Fuel: neg; Water: neg; Gylcol Neg.

The car's last oil change was Dec 2002 at 89059. I purchased the car in oct 2003 at 89177 miles. Yes, less than 200 miles in the year. The owner passed on in 01-2003. I put 2000 miles on the vehicle and had the oil sampled. Antifreeze test is negative.

No oil needed to be added in 2000 miles.

TBN at 8.50; viscosity 15.3

any suggestions or comments. I am leaning that because the car sat for nearly a yearly, that could have something to do with the high K levels.

BoostnBenz · #2 01-07-2004, 12:12 AM

I'm not sure what causes high K levels, but the oil has quite a bit of life in it still since the boron is still so high. I presume you took the same at 2k miles solely to test for antifreeze?

Palangi · #3 01-07-2004, 12:42 AM

My 300D came back with elevated potassium last time also. Supposedly the primary suspect is antifreeze, although the water and antifreeze were both 0.0%. (Of course, the water and antifreeze are measured down to 1/10 of 1%, while the potassium is measured down to ppm's).

Some oils contain potassium, but the oil I have been using does not. I am 2000 miles away from the next oil change, so it will be interesting to see if there is any change. If it goes up, I guess it could be a sign of a head gasket leak.

gsxr · #4 01-07-2004, 03:53 PM

Generally potassium indicates anti-freeze in the oil, since the water boils off, and the glycol may not show much either. It can be from other things though. Rotella ain't all that great, try Mobil or Amsoil synthetics if you can afford it, if not then use Delvac-1300 or Delo-400, which are a much better product than the Shell. Do a search on this forum, oils have been discussed ad nauseum here!

autozen · #5 01-08-2004, 10:13 AM

fj,

You can't use the raw data from the sample unless you extrapolate it. The full recommended oil change interval should be over 5000 miles. You tested at 2000 miles, and suppose you had checked it at 200 miles. What would those results have been? In my opinion oil should be sampled for trace elements after it has run its full course following mfg recommended intervals.

Boostnbenz,

Please explain boron and lots of life left in oil. Thanks.

Peter

#6 01-08-2004, 10:21 AM

quote from gsxr:

"Rotella ain't all that great"

Where did you come up with that?

What is wrong with Rotella?

gsxr · #7 01-08-2004, 11:37 AM

Quote:

Originally posted by oilburninokie
Where did you come up with that?

What is wrong with Rotella?

Do some searching on this forum about oils. Rotella is, as Doc Booth puts it, "ordinary" oil. It's very likely better than the no-name Wal-Mart and McParts oils, but it's just a notch under the really excellent diesel-specific oils like Delvac-1300 and Delo-400. If you're going to use dino oil in a diesel, I'd only use one of those two. But that's just me.

Also, Rotella "synthetic" isn't synthetic, it's a Group III (hydrocracked dino) base stock, not a true Group IV/V synthetic like Mobil, Amsoil, and Red Line oils. I dislike deceptive marketing and lose respect for manufacturers that resort to those tactics (Castrol SynTec and Valvoline are also Group III 'synthetics' - I wouldn't use them either.) The Group III stuff is probably better than most dino oils, but it can't tolerate extended drains, which is one of the main benefits of synthetics in the first place! Why pay twice as much and have to drain at the same interval? True synthetics let you get all the benefits, but offset the cost with extended drains. Sorry, didn't mean to get off on a synthetic rant, but I'm a big proponent of them... I use Delvac-1 and Mobil-1 in my cars.

JHZR2 · #8 01-08-2004, 11:50 AM

Sometimes potassium can be a trace additive... But can certianly be indicative of a headgasket issue, etc.
I would be interested in seeing your Silicon (Si) readings, as that will shed some insight into the wear levels. 2000mi is way low to have such high Fe levels. But, if you have some sort of intake leak or a dirty/lousy filter that is letting junk pass through, the resultant junk in the oil (usually shows up as Si) will greatly increase wear. Lead and copper are reasonably low, telling me that bearing wear isnt bad, all the more reason to check for intake issues.

Rotella is, Id say, in the lower tier of the diesel oils. Its like any oil, if you change it in the right interval, itll make your engine last for a long time. However, there are better oils that will yield better economy and less wear of certain parts. Rotella has negligible molybdinum additives, which is a really great antiwear and economy enhancer. Delvac 1300 and pennzoil longlife has it in a nice shot. Delo doesnt have it, but its cold temp specs more than make up for it... delo is a high quality hydrocracked oil. Rotella doesnt have very good cold temp properties, nor does it have an additive package that is anything special.

I found personally that my worst mileage was obtained with rotella and especially delo 400...

JMH

blacksmoke · #9 01-08-2004, 01:44 PM

i've been using rotella t synth in my 240 since walmart starting carrying it. get it for like 13.00/gal.

will probalby switch to delvac1 when i can afford it, heard too many bad things about rotella at truck stops.

JHZR2 · #10 01-08-2004, 02:54 PM

Rotella "synthetic' Isnt really synthetic at all... Its group III petrolleum.
That said, the price is right, and Id use it in lawnmowers and stuff that wont necessarily benefit from mobil1 type synthetics, but could use a little wear reduction or need to stop burning so much oil.

All I can say is at least shell charges a reduced price for their fake synth, unlike castrol who charges M1 prices for their group III fake synthetic!

JMH

gsxr · #11 01-08-2004, 03:08 PM

Quote:

Originally posted by JHZR2

All I can say is at least shell charges a reduced price for their fake synth, unlike castrol who charges M1 prices for their group III fake synthetic!

JMH

Amen! That's their one saving grace, the lower cost - at least when it's on sale. One side effect of the Group III stuff is that oil consumption may increase after 4-5kmi on the oil. Marshall Booth saw that repeatably with SynTec 5W-50, the engine would start to burn oil after 4-5kmi, but when the same engine was switched back to Mobil synthetics there was no such behavior - consumption remained linear up to the 7-10kmi change interval.