Coolant question

[BENZ-LGB]

I have followed of member K6JRF regarding the right coolant mixture/ratio.

I keep the water/coolant ratio to 70/30 as suggested by K6JFR.

See:

http://pages.prodigy.net/jforgione/MB_S500.html

Today I drove my 1989 300TE (197k miles) in the San Fernand Valey. Stop and go traffic. A/C on high all the way. Ambient outside temperature were over 100 degrees. My car's temperature never went over 100 degrees. So i am pleased with my current situation.

My question is: am I hurting the car in any way by running such a high water to coolant ratio? Every mechanic that I have talked to suggests at least a 50/50 ratio.

My car runs wells but, again, am I doing something wrong?

Thanks for your input.