Coolant longevity and other stuff.

[doitmyself]

Engine cooling system problems from neglect can be as big a pain in the @ss as just about anything else.

With the old conventional coolants, I changed them every two years and never had problems.

All of the new coolants suggest 5yrs. or XX miles/hours is now acceptable. Whether it's OATS or HOATS,........or little lambs eating ivy.

Even my John Deere SCA(Hoat) fluid says 5yrs. IF YOU MONITOR and ADJUST SCA annually.

So, what's the verdict? Is 3,4, or 5 years safe?

Help me out, I'm stuck in the ice age of every 2 years, regardless of coolant. Is this akin to 3,000 OCI's and flushing brake fluid every year??

Thanks. I would like to hear some real world experience, both gas and diesel applications.

 

[Stinky Peterson]

The only way to know for sure is to have a coolant analysis performed by a reputable lab. This is advisable for diesel engines but might be hard to justify for gas engines since they tend to have small capacities and it it probably cheaper to just change the coolant periodically.

There are many variables that can affect coolant degradation so it is hard to come up with a good rule of thumb. To start with I would at least consider the manufacturer's recommendation, especially if you are under warranty. If the system was cared for properly and always topped off with the correct (matching) coolant and not pond water or concentrate then it should last as advertised. Unfortunately bad electrical grounds, hard driving (elevated temperatures), improper top-off, hard water, air entry, improper additive use, etc. can all cause problems.

If the coolant looks clear and bright and is at 50% then it is probably OK. Lower concentrations don't provide adequate additive or boil protection and hot coolant (even localized overheating) increases the rate of scaling, additive breakdown, corrosion, and acid formation. Glycol breaks down to form several different acids (glycolic, oxalic, formic, etc.) and this is greatly accelerated with heat.

Fortunately many common problems show up as cloudy coolant or as various precipitates in the coolant so collect some in a clear container and if it isn't clear then consider changing it or having it tested. Diesels need to have their additives checked at every oil change if you are using conventional coolant or quarterly if using extended life coolant (at least until you can establish a depletion rate). This can be done using test strips but there are many different coolants/additives with different recommended levels. Try to get the same brand test strip as the coolant/additive you are using but be aware that they spoil very quickly so it it best to get the ones that are individually wrapped. A bottle of strips will spoil if opened for as little as an hour (total opened time) so I do not recommend using them unless you have a fleet and even then your are better off having a lab help you decide what to do when.

 

[Big Jim]

I change mine once a year, even the long life stuff. Doing so, I still have original hoses and thermostats that look to be perfect at well over 200,000 miles.