As said rust is the enemy.
I had a 1989 240GLT for 10 years and 8 as only daily driver car.
The B230E is a great engine and mine was Automatic. A good combo for me. I added 72,000 miles on my 240 and very reliable and very trouble free. Sold at 234,000 miles and have a 940 now.
Highly rate a late 240.
James.