My wife's 99 ML430 has approx. 80K miles and has been treated with synthetic since new. We are currently using Mobil 1 15w50, but I've noticed that 0w40 has been suggested for use by other ML owners. I'm getting ready to do an oil change next weekend and would like to make the change then. I live in Southern California, where temperatures never get much below 50*. Would it be acceptable to change at this point or should I stay with what I have? What are the pros and cons?

Thanks!

 

I'd go with the recommendation made by M-B. Look in your owner's manual, or maintenance manual, whatever. Why do you think ML owners would trump M-B engineers?