tapdancer

Oil Analysis Results:
1. All data indicate that sample oil is satisfactory and no action necessary at this time. However,

2. 57.5% of TBN was depleted over 48.9% of OEM recommended service interval. (See driving profile and Engine oil history below)

"Total Base Number (TBN)

TBN is the measurement of the reserve alkalinity of the oil's additive package. The lower the TBN in relationship to the new oil, the less its ability to clean the system and suspend contaminants." per Herguth Lab.

Engine Oil History:
1. Added 1-qt Mobil-1 0W30 synthetic at 2,500 miles (on top of factory-fill).
2. First Audi "Free" service performed by dealer at 10,195 miles. Added 3.7-qt Mobil-1 5W30 synthetic (I provide oil).
3. No oil added between 2,500 and 10,195 miles.
4. First oil analysis sample taken at 15,089 miles. Sample saw 4,894 miles.
5. Added oil to replace sample taken at 15,089 miles.
6. No oil added between 10,195 and 15,089 miles.

Driving Profile of miles:
Speed:
* 62% greater than or equal to 55 mph.
* 38% less than or equal 45 mph
Time:
* 62% greater than or equal to 20 minutes.
* 38% less than 20 minutes.

rexti_98

Confusing

AggregatVier

So, basically, 10,000 mile oil changes are no problem.

tapdancer

Depends on your driving habits and conditions. I am in South Florida and with my driving style the analysis is implying that the additive package may last just about 10,000 miles. I'll take the next sample prior to having the second "free" service. If I don't need to add any oil by then, I'll know the total depletion over the interval. At that time I'll decide if the oil or drain interval is adequate...... for me.

BigPatsFan

62% of the time your speed was greater than 55 mph? How did you ever track this? Also, why did you do the oil analysis at 15,089 miles? Why not at 10,195??

tapdancer

To estimate the driving profile, I tabulated my typical monthly driving pattern for both work and personal. Noting trips on highways (some with legal speed up to 70 mph)and local roads with limits up to 45 mph.

Based on each trip, I know how long between starting the engine and shutting down. This time will indicate whether the oil reached a high enough temperature (and long enough) to get rid of potential condensation.

I did not take a sample at 10195 because the oil removed was basically factory fill, with the 1-quart added at 2,500 miles. Analysing the used factory fill would have served no useful purpose. A sample of the M1 5W30 SuperSyn at that time would have served the same purpose as the referenced (unused) sample that was provided and analysed along with the used oil taken at 15,089 miles.