Either way works!
I 'tweak' my mixture by removing some from the overflow reservoir (OR). So if mixture is close, it works great.
On my car, the OR holds a little over one gallon, which is apx 25%of the total. So you can get to 40/60 (af/water) ratio very easily.
Yes, Prestone checker works great with EG since that's the main ingredient in MB af.
Regards . . . . JimF
'94 S500 Cpe
Visit my Mercedes Web Page
Last edited by JimF; 06-21-2002 at 01:31 PM.