[doyall]

See attachment.

This test came immediately after a 250 mile return trip home and was conducted to determine if the previously existing fuel dilution to the oil would be mitigated by evaporation resulting from extended use at operating temperatures. The answer is yes, to some degree. Fuel dilution came down to what the lab called "normal," but obviously not far from returning to "abnormal." My estimate is that after one week of typical use (cold start then 10 mi to work, cold start then 10 miles to the gym then 2 miles home on Mon. thru Wed., with Thur & Fri. being cold start then 2 miles to gym, 2 miles home, 10 miles to work, cold start then 10 miles home) the dilution number will be back up. (I say that because the first test I posted consisted of that same typical weekday driving which immediately followed a 400 mile day trip.)

While I will still hold out hope that after a proper wear-in things will change, it is a very slim hope indeed.

 

[Wayne]

FWIW here is another oil analysis on a car mostly used for short around town trips. This is a 2017 GLA45 at 26,619 miles with previous oil change done at 19,494 miles.

While this test advised a longer duration between changes I note a potential breakdown in viscosity (not uncommon for Mobil One but possibly a fuel dilution problem) that will make me enforce a 5K mile period next time.

 

[Audi Junkie]

Mobil 1 reacts poorly to fuel dilution. It damages the oil both chemically and physically, which cannot be undone by "evaporation".

I would try again with a 5w-40, or umm, cough...Rotella.

 

[Huey52]

I hold to 5k oil changes with Mobil 1 0W-40 European Formula. Oil analysis is a prudent way to go. As Wayne, I like to do so at low mileage and then periodically prior to changes to form a track record from which I can discern any irregularities.

 

[Audi Junkie]

I go with timed intervals of either 6 months or 12 months. I plan my changes in Fall and Spring, so I never have to go out to do it in the cold. Cars that get two changes a year sometimes get a different visc for winter, and 5w-40 can be quite thick in cold, getting pumped thru the turbo oil lines. Non-turbos are fine with a few cold starts of thick oil.

Timed intervals, 6 months ideally, covers both short trip drivers as well as those who drive a lot of highway miles, both need an OC after 6 months just the same. Usually I leave the old filter in for those changes.

My 12 month changes are for cars that see only 6000-8000 in a year. At 9000 miles, you may as well do two changes. We have a nice fleet going at the moment, not including my mother-in-laws Jetta Sportswagen 2.5. The white Golf SW is my wife's, a 6-sp with JB4 tune.