I have not heard the theory before that one need NEVER change oil if one changes the filter. Just changing the filter would protect against gritty contaminants, but not against gasoline "blow by".
That being said, a very qualified tech who is a professional restorer of vintage Mercedes argued that only the filter needs to be changed mid way in the manufacturer's recommended interval. And with Mercedes top-mounted filter, it is easy to do this, without getting oil in the face!
__________________
The SLK -- What the SL was supposed to be. |