# Oil Analysis/2002 Audi TT Roadster



## TooSlick (Feb 17, 2000)

1.8L/225 Hp engine (stock)
6 speed manual 

Miles on engine, 96,250
Miles on oil, 6250 (oil installed 12/2010 & tested in 2/2013)
Driving is mainly short trips of < 20 miles.
OEM, air and oil filters 
Oil used, Amsoil Series 3000, 5w-30
Oil added, 0.5 quarts
Oil sampled hot through the dipstick tube using a suction pump

Wear Metals:

Fe, 8 ppm
Cr, 0 ppm
Ni, 0 ppm
Al, 2 ppm
Cu, 18 ppm
Pb, 0 ppm
SN, 0 ppm

Contaminants:

Na, 4 ppm
K, 4 ppm
Silicon(dirt), 5 ppm
Fuel < 1.0%
Soot < 0.1%
Water < 0.1%

Oil Additives:

Mg, 27 ppm
Ca, 3280 ppm
P, 953 ppm
Zn, 1102 ppm

Physical/Chemical Properties:

Viscosity @100C, 10.7 Cst (baseline is 11.7 Cst)
TBN, 4.32 (baseline is 12.0)
Oxidation (abs/cm), 53*
Nitration (abs/cm), 14
* Organic esters in base stock generate high apparent oxidation levels.

Notes:

I don't drive this vehicle much, so oil was in service a bit over two years (short trip driving). The Series 3000, 5w-30 is marketed as a fuel efficient, HD diesel oil. However it also meets the generic "ACEA A3/B3" ratings and I've had excellent results with it in VW/Audi engines over the past 15 years. I actually think its their best, "full SAPS", European oil.

I'll be glad to entertain any questions....

TS


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## BsickPassat (May 10, 2010)

....so, the Amsoil Series 3000 has organic esters?

What's the baseline TAN?


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## brownchicken/browncow (Dec 20, 2011)

TooSlick said:


> 1.8L/225 Hp engine (stock)
> 6 speed manual
> 
> Miles on engine, 96,250
> ...


I'm not getting why anyone who thinks they are such an oil aficionado and knowledgeable about everything would leave oil in an engine for 3 years especially when said car only does short trips! :screwy: Checked your brake fluid recently? :sly:

:laugh::facepalm::laugh:


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## TooSlick (Feb 17, 2000)

TAN or "total acid number" is only really useful when evaluating the service life of ATF or gear lubricants. I flag the TBN when it drops to 1/3 the baseline TBN (for labs using the ASTM D-4739 test protocol) and change before it drops to 1/4. In the particular case of Blackstone Labs, I'd flag the TBN when it drops below 1/4 of the baseline and change when it reaches 1/5 of the baseline value. Amsoil is primarily PAO based and the ester is used as the carrier fluid (solvent) for the oil additives, to balance out the elastomeric seal swell characteristics and to provide some increased lubricity. 

As for the wisdom leaving the same oil in for over two years.... I've done this on multiple occasions and the oil (and engine) always tests out fine. Back when I was driving the TT a lot I stuck with 10,000 mile change intervals of less than one year with results very similar to this. I also like to overtest products with my own vehicles and outdoor power equipment (OPE), before I feel comfortable recommending them.


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## brownchicken/browncow (Dec 20, 2011)

So, I guess you're checking your brake fluid, now then! :laugh:


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## TooSlick (Feb 17, 2000)

I'm actually pretty AR about changing brake fluid, since it's hygroscopic. Several decades ago I tried one of the first generation, silicone based (DOT-5) brake fluids in a Datsun 620 pickup, which turned out to be a disaster. The water settled out and corroded everything. Sometimes you learn the hard way...LOL


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## BsickPassat (May 10, 2010)

TooSlick said:


> TAN or "total acid number" is only really useful when evaluating the service life of ATF or gear lubricants. I flag the TBN when it drops to 1/3 the baseline TBN (for labs using the ASTM D-4739 test protocol) and change before it drops to 1/4. In the particular case of Blackstone Labs, I'd flag the TBN when it drops below 1/4 of the baseline and change when it reaches 1/5 of the baseline value. Amsoil is primarily PAO based and the ester is used as the carrier fluid (solvent) for the oil additives, to balance out the elastomeric seal swell characteristics and to provide some increased lubricity.
> 
> As for the wisdom leaving the same oil in for over two years.... I've done this on multiple occasions and the oil (and engine) always tests out fine. Back when I was driving the TT a lot I stuck with 10,000 mile change intervals of less than one year with results very similar to this. I also like to overtest products with my own vehicles and outdoor power equipment (OPE), before I feel comfortable recommending them.


TAN is still a useful number... when TBN drops, TAN rises. The company that did the UOA, specifically pointed out organic esters in the oil.

Since it's just for the additive package.... which is interesting, because there is a disconnect with the UOA company


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## TooSlick (Feb 17, 2000)

Oil Analyzers Inc (OAI) didn't point out anything. However I've been doing oil analysis for almost twenty years and have reviewed hundreds of samples. So given the parameters of this analysis and the fact that the oil hasn't thickened I can conclude with a high degree of certainly that the false oxidation spike is from organic esters in the base oil blend. If you were to test something like Redline Oil, you'd see an even bigger spike. As you may know, certain types of esters have a wave number similar to the by products of oxidation when viewed through FTIR. I see this false oxidation peak when testing this particular oil, along with the Amsoil Signature Series product line.

I think I understand the relationship between TBN and TAN well enough. However if you use a conservative condemnation limit for TBN you really don't need to be concerned about the TAN of used engine oils. There's no real sign of corrosive wear here, except for some minor elevation of Cu levels (vs my 5-6 previous analyses of this motor). I believe this is simply some leaching of Cu from the oil cooler/heat exchanger, caused from using the same oil for so long.

TS


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## shortybdub (Oct 14, 2011)

Those familiar will conclude the organic ester did/does contribute to the oxidation numbers, just look at the soot and nitration numbers. When those are this low and the oxidation number is high, you look at the esters. 

Haven't kept up with OAI and their protocals (being the Terrry Dyson fan that I am l), other than they use Fournier, how do they test fuel? Open cup like B-stone, or closed cup?

BTW, this sample looks very good for what you've done.


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## BsickPassat (May 10, 2010)

shortybdub said:


> Those familiar will conclude the organic ester did/does contribute to the oxidation numbers, just look at the soot and nitration numbers. When those are this low and the oxidation number is high, you look at the esters.
> 
> Haven't kept up with OAI and their protocals (being the Terrry Dyson fan that I am l), other than they use Fournier, how do they test fuel? Open cup like B-stone, or closed cup?


oil analysers uses closed cup


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## shortybdub (Oct 14, 2011)

BsickPassat said:


> oil analysers uses closed cup


Good deal, better accuracy for overall fuel content. Made me wonder though, because the vis is down a bit. Thought of fuel dilution because of the short trips.


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## TooSlick (Feb 17, 2000)

The Cleveland, closed cup & open cup test methods are used for flashpoint and not fuel dilution. I believe OAI uses an IR scan for determine fuel dilution. I'd imagine there is some fuel in this sample, along with a bit of polymer shearing. This particular formulation does hold up very well in that respect, however.

TS


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## shortybdub (Oct 14, 2011)

TooSlick said:


> The Cleveland, closed cup & open cup test methods are used for flashpoint and not fuel dilution. I believe OAI uses an IR scan for determine fuel dilution. I'd imagine there is some fuel in this sample, along with a bit of polymer shearing. This particular formulation does hold up very well in that respect, however.
> 
> TS


True, True. I always look at the fuel numbers as an indication of dilution, since excess fuel in the oil (dilution) will generally cause the reduction in flashpoint. While this is not correct per se, it does help me reconcile it in my tiny mind .

T-that formula DOES look good despite long (timewise) service interval.


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