My 91 350SDL has 318k miles. We started running blends in the stock tank without any modifications at around 180k miles. At around 225k miles, I installed a single tank kit and ran nothing but vegetable oil all summer and blended in the winter months (I live in a relatively warm climate). My daughter drove the car to college for two years this way. A part on my plantdrive kit broke that I could not find or fabricate, so I went back to diesel and blending for a while with no kit. About 6 months ago I installed a new single tank kit from Mercedes source and injector line heaters from fatty wagon. So now I'm back to running straight veggie oil again, until the coldest months, when I will blend. I've never even had the screen out of my tank, even though I'm sure it needs cleaning (on my to do list). The key is clean oil and the type of oil you use. I've always had peanut, soy or canola oil. I have an advantage because I own a restaurant so I can control and know what I'm getting. I don't filter it, but I settle it twice for weeks at a time. A filter on my car last for months. I drive the car approximately 100 miles each day, its my daily driver.
I understand that this doesn't work for everyone, but it does work for some. I think the key is clean oil and using common sense.
Good luck with your sale. It sounds like this has been a great car for you.
