The 88 300ce service schedule is every 7,500 miles (for oil change and other minor things.) Heavier stuff comes at 30,000 (and other) mile intervals. If I remember correctly my 88 300ce fuel injectors were first replaced at the 45,000 service. At 60,000 the dealer service was a bigger hit. Just today made an appointment for my 75,000 service, which didn't list any big items as I recall.

So, 150,000 on your odo indicates that it's time for some recommended scheduled maintenance.

I assume you have previously inspected the serp belt, pads, rotors, and suspension items, ball joints, motor mounts etc, etc.. These would be some of the items to be replaced at the longer intervals.

If your oil consumption is high, look into changing valve seals. I had to replace mine 2 years ago (when I had about 58,000 on the clock as I recall)
End of problem.

You own 1 of only 2,734 W124 coupes sold in US that year, which fyi had an MSRP $52,500.
I hope you enjoy driving yours as much as I do mine.

Jim