Keep Sinking Money or New Engine?

[TiAgX5]

Originally Posted by trader4

IDK what exactly the BMW system monitors, but in general, I thought that cars with similar systems do monitor a number of driving parameters, including short trips, to determine how soon an oil change is due.

And IDK what data those that say the oil isn't being changed frequently enough are relying on. There are a wide array of opinions. Jiffy Lube will tell you to change oil at 3000, whether it's conventional or synthetic. I think that's nuts and they have no data to back it up. Is going to 15K the best practice? Probably not, even BMW apparently has now reduced it to 10K. Is it based soley on saving BMW the cost of oil changes on the first 100K miles? I don't think so. For example, my Porsche 911 also had a 15K oil change recommendation and it did not have any free oil change program period. The tradeoff of having cars with engines that are shot at just past 100K miles, while saving the small cost of 3 additional oil changes, isn't one that I think a rational manufacturer would make.

I think pushing the oil change interval can have an effect on the life of an engine. But I don't see following the BMW suggested oil change interval being the reason a car needs a new timing chain, new valve seals, has all kinds of leaking gaskets, etc at 100K. There are a lot of other quality related problems with these cars, eg window regulators that break and fall down, CV boots that fail at 3X the rate of other cars, FSR blower resistors that suck, an aux fan from hell, etc. How about that great oil separator design, that when it fails, can trash the whole engine? And most of those things are ones that decent replacement parts could easily fix over the last 14 years, yet we still have the same sucky parts. So, I don't buy that the engine problems are necessarily the result of 15K oil changes.

The newer (post-'06) SII oil monitor system monitors operating temps, dusty condition (with the HVAC auto-recirc dust sensor) and conductivity of oil (dirty/thin oil has a different electrical resistance then clean/new oil).

I change oil at 60% SII oil life (3rd green LED goes out, so does the oil/filter).

I avoid Iffy Lube at all cost, they don't stock BMW filters and fill with non-LL-01 spec bulk oil, sometimes a recycled blend! Seen too many stripped oil pans that they claim "were that way when it came in"!!!

I'm still running OE TC guides at 185k miles, and 3 FSR changes, 2 don't count, went with $40 e-bay FSR that failed in a few mos, returned for exchange and replacement failed too. $130 BMW sourced FSR has worked fine for over 3 yrs now.