Unofficial Maintenance Schedule?

ATF: as soon as possible, it's pretty much impossible to change it too soon. Judging from the drains I've done: the break-in period is by far the time the most deleterious stuff mixes in, from thereon: no so much.

Coolant: meh, stick with the schedule, and note it is miles OR months, if that matters. Also note: the inverter coolant change interval (at least in the States) is 50% further down the road, if you follow the trail to footnote 3:

 

I like simple, easy to remember service intervals. For instance, I do oil changes at 5K miles for conventional oil, or 10K for synthetic. So I don't even have to look at my service records to know if I'm due for an oil change. I just look at the odometer: if it's approaching a "5" or "10" it's due.

Having said that, I'd do the ATF every 50K, and the coolant and spark plugs at 100K. That's not based on any engineering knowledge I have of an optimal service interval for these maintenance items, it's simply easier and within recommended intervals.

Just my 2 cents. After adjusting for inflation and current market conditions -- arguably worth that!

 

Sign up with car fax, you get to see all intervals w specific maintenance. Even email alert when a maintenance is due within weeks and days.

 

Here's a spreadsheet of the US schedule, per the book. I make these up just to make sense of it. Not necessarily advocating what's in it, just summarizing it.

 

I never noticed the 50K mile interval for coolant after the first change. On the surface that would seem illogical -- I mean, if the OEM coolant from the factory is good for 100K in the engine and 150K in the inverter, why would it only be good for half or one-third that later on? Well, I figured it out yesterday while doing the EGR cooler service and coolant change.
I drained at the radiator and got about a gallon. Then removed the block drain (or more precisely, where Toyota used to put a block drain) and zero coolant came out -- not surprisingly since it's located halfway up the block . I figured, "Great, the block must drain back to the radiator." Incorrect! When I removed the EGR cooler, about a cup of coolant spilled out. Which indicates to me that theres still coolant in the engine cooling circuit, and short of removing the engine and turning it upside down, it's impossible to completely drain the cooling system.
So we're always mixing old coolant with new, which explains the unusually short interval.
I'm a little disappointed. Toyota specs a coolant that's good for 100K miles, then designs an engine that can't take advantage of it. In this day and age, a 50K coolant change interval is unacceptable, IMHO.

 

There was also another newer member throwing a theory around about coolant breakdown over time and longer drain interval leading to head gasket failures.

Not sure myself on that, but I will be doing the engine coolant loop every about 50k miles going forward which will coincide with an egr swap and spark plug change since I have the windshield wiper cowling off.

Based on the last round of egr circuit cleaning and knowing our 2010 with 177 k miles on it consumes about a quart of oil every 5 k miles, that 50 k mile frequency seems appropriate.

The cooler will be clean and ready for round #3 when 225 k miles hits

 

Why can't you hook up one of those machines that clean the coolant and recycle it through the engine. If you left the hose off that returns the coolant to the engine, couldn't you get all the coolant out that way?

 

@tvpierce I've seen several mentions here, that the Prius engine block coolant drain spigot spigot yields little or no coolant. Kind of surprising: all our previous Hondas, removing the engine block coolant drain, there was biblical coolant floods, usually hard to catch too, you would be lucky if half ended up in your catch basin.