Old coolant not all flushed out : What to do?

[Tourist]

Hi. Decided to remove the already 5-yrs old 100,000-km Texaco Extended Life Coolant from my Isuzu diesel engine. The radiator capacity is listed as ~8-liter. When the mechanic removed the old coolant and poured in the new Texaco coolant, could only manage to pour in 7-liters of the new coolant. That means there must be ~1-liter of the old stuff still inside the engine block somewhere. Well, too late to do anything now so would like to ask your opinion as to what's going to happen.

Another thing. Texaco stuff is orange-red in color but when we removed the old coolant, it's clean but green in color! What's happening?

Thanks.

 

[Ray H]

The rule of thumb about mixing antifreeze types from stateside sources is that if there's old content in excess of 10%, the working life of the new coolant will be compromised downward. From your figures, you're at just under 15% of already exhausted content. You're probably safe for two or three years (maybe even longer, but I wouldn't push it). But next time insist on a full water flush to remove all the old coolant before you introduce fresh coolant into the system. (Five year old green coolant doesn't sound like a long life formula to me, but I'm not familiar with what's commonly available outside the U.S. The fact that it drained clean is reassuring, though.)