Originally Posted By: Audi Junkie
Firstly, you didn't say exactly what was wrong with it, other than being "silly".
Oil isn't going to go bad just sitting in the sump--so a time based interval seems silly to me in light of better information.
Originally Posted By: Audi Junkie
Secondly, it's just blanket advise that happens to work well for both short trip driving as well as long highway drivers.
Not really. If someone drive his car twice a week for 40 miles at a time, or every day making a bunch of shorts trips, should they both be changing their oil at the same time? Under your plan, they would be. That, to me, is silly.
Originally Posted By: Audi Junkie
Assuming he uses the car every day, is it several short trips, that is hard on the oil or is it long highway trips, that are not in itself hard on the oil, but consuming fuel does affect the oil condition negatively.
THAT'S THE WHOLE POINT OF THE OLM?? I does not treat all miles the same. It's not a mileage countdown timer. It's taking into account all of the external variables (oil temps, number of engine revolutions, engine load) which make short trips harder on the oil.
Originally Posted By: Audi Junkie
So I'll ask in return, how are timed intervals worse than miles-based intervals? In my analysis, time makes a lot more sense. Of course following the OLM is one approach, but it didn't appeal to me at all, being just a footnote when I decided to change.
See my example above. I understand using time as a proxy for shorter trips, but some people drive infrequently, and for longer distances when they do drive (this sums up the driving habits of a lot of bike commuters I know).
Originally Posted By: Audi Junkie
I change visc for seasons, and also am aware that the cold-cranking ability of the oil diminishes in duty. So, why would I want to go into deep winter with 90% worn out oil...just to have to get on the ground in Jan or Feb to change it just because the OLM says so? That's a different kind of madness, imo.
The OP's car does't call for a change is viscosity, since it's using a light oil anyway.
Originally Posted By: Audi Junkie
I'm not sure the OLM is ideal anyway. It's a maximum oci. Remember too, the friction modifiers wear out.
It's not a "maximum OCI". It's designed to leave roughly twice the amount of necessary additive for the recommended oil (at least all of the OLM's I've seen are programmed that way). Can you show me a single UOA in a sound, unmodified engine where the oil didn't contain enough additive, or wasn't suitable for use, following the OLM? Just one?? Sure, additives wear out. I've yet to seem them wear out over the course of a OLM-suggested interval--have you??
Originally Posted By: Audi Junkie
A cheap oil change brings back a better engine feel, for sure.
Good god....so in the end, we're left with the placebo effect of a "smooth engine" after an oil change and the "cheap insurance" line of Jiffy Lube commercial? It's not "cheap insurance", it's unnecessary and wasteful.
Again, I have yet to see any rational reason to NOT follow the OLM.