Oil and tire pressure?????

[kmancars]

Dear members, what's the big deal with synthetic 5-30? What common sense lapse does BMW use to state oil changes at 12K intervals?

On a different matter, how much leway do I have with tire pressure. I now am running 235-45-17s on all fours. Mich sport pilot2s can I set at 30 psi on all to dampen ride qual. Then up the psi when I plan fast running? Thankyou

[Crimson92]

Originally Posted by kmancars

Dear members, what's the big deal with synthetic 5-30? What common sense lapse does BMW use to state oil changes at 12K intervals?

On a different matter, how much leway do I have with tire pressure. I now am running 235-45-17s on all fours. Mich sport pilot2s can I set at 30 psi on all to dampen ride qual. Then up the psi when I plan fast running? Thankyou

bmw pays more maint, the less often they have to change your oil, the less they pay. plus our cars have been optimized to run on those intervals...its really not a big deal imo.

at 30 psi youre running the risk of causing premature wear on your tires


you bought a z4...and you want softer ride quality?

[vachss]

Originally Posted by kmancars

Dear members, what's the big deal with synthetic 5-30? What common sense lapse does BMW use to state oil changes at 12K intervals?

Why would BMW want your car to last 250K miles? I and many others here change oil at 5000-8000 mile intervals.

[kmancars]

Yes I do want a better ride, something akin to a Aston Martin, or a Maserati. I was a little to kind to BMW on oil. I think they rec. 15K intervals. Who knows, BMW must think owners are not to be trusted? They do not indicate intervals in the owners guide??
As far as our Z4's being optimized for long intervals, I do not think you could find an engine builder who could support this position on technical grounds. Contaminants get past your cyclinder walls weather it's a Bimmer or a Bentley Superspont.