I have religiously changed the coolant in the E300D every three years. This year marks the three years since the last time I did it. But the E300D has kind of been relegated to being a little used garage queen for the past four years or so. I've put 12,000 miles on it in three years since the last coolant service. I checked the coolant today and it is nice and clean, good to minus 30 and is giving me a reading of under 100 mv when I tested it with my multi-meter. It's got Zerex G05 and distilled water in the system now and keeps a nice steady temperature of around 165 to 170 when driving.

I was all set to do it, but after today's checks, I'm thinking it can easily go another year or more.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles