Scotty or moderator,
First time posting, long time viewer. I am a bit confused about the new 0W20 oil for the newer BMW models. My wife owns a 2015 BMW 428i with 85K and the car used to get (we got it second hand, but in excellent condition) oil changes with the previous oil recommendations of 5W30 full synthetic. I have read from others that even though BMW has now included the new 0W20 oil as the preferred oil weight, a lot of people believe this is just a ploy to have BMW reach CAFE goals with their GDI engines for economy use, and sacrifice reliability issues by dropping the 5W30 LL-01 based synthetic oil. It kinda makes sense as the heavier oil would protect and cool the engine more than the thinner weight. But maybe there is some manufactured magic to this oil that allows a thinner weight to be used in a high compression, turbo'd four banger. But then again, this would not be the first time BMW has sacrificed their customer base to achieve their corporate goals. Such as lifetime transmission fluids in the older automatic transmissions. I was wondering on your thoughts on the oil use, is it worth the risk or is there actual benefits to using a lighter weight oil for these engines? Also, can you explain why the need for a startup time and cooldown time for turbos are no longer needed? I remember turbo timers were the must haves back in the day to prevent the oil from cooking in the turbo making a coking problem that would destroy the turbo prematurely. Or in the case of startup time, to prevent oil starvation in the turbo until the oil flows better when first starting a cold engine. Thanks and if you are answering this ridiculously long question, God bless you for having the guts to state the facts and not be a lemming and kowtow to the corporate mantras for greed sake.
- Amrathe
@amrathe
What does the cap on the oil filter say? Use that oil.
The question you're asking is debated across the entire automotive community. The general consensus seems to be partly that manufacturers are trying to squeeze out every MPG they can BUT in so doing are also increasing the tolerances of engine assemblies. The viscosity issues is not just about protecting the engine, its also about protecting the engine while allowing it to freely move and operate within acceptable tolerances. It will take at least a decade before we know for sure if an 0W-20 oil causes premature wear to the engine in your specific vehicle but if the manufacturer recommends a thicker oil AND you live in a mild climate then I would stick with that. Bear in mind that a majority of the wear in an engine occurs when you start the car and oil has not made its way through the passageways. Too thick of an oil can actually take too long to reach vital parts of the engine and cause more harm than good.
@inthedetails
Thank you for your fast reply. I do live in the NJ area which would qualify as mild but seasonal as well. I guess it would be best to stick with the LL-01 oil base as it was shown as the original oil type the car was engineered for and hold off on the 0W20 stuff for now. Would you know perchance the issue about the turbo timers and the old ritual of waiting for two minutes on startup on a cold engine and two minutes on a cool down period after long periods of driving to prevent oil issues with the turbos? - Amrathe
@inthedetails
The turbo ritual is to let the poor hamster cool off using the oil. Because the alloys used were very fragile at high temperature. The oil would take the excess hear away at idle. Modern turbos MAY not need that as they have benefited from metallurgy developments.
By "waiting two minutes" do you mean letting the car idle for a few minutes upon start-up and during a cool down period?
The general consensus is the best way to decrease wear on turbos for the purpose of extending their life is to use an oil cooler.