I get my pH checked. I'm hyper vigilant with my maintenance. I'll be doing a trans drain and fill soon when I get my next oil change. I need this to literally last as long as humanly possible or at least until the rust takes it over at some point in a decade or two.
I'm not too worried about rust winning the battle, had NHOU oil sprayed inside body cavities as soon as I got it and wool wax on the frame and undercarriage this year. First 4 years it spent winters in Texas one of the reasons I bought it. So far looks like winning the battle although fighting rust on steel ships in salt water and air with 100°+ temps for 20 years not sure it is a battle you ever win. But can keep it in check. Have a heated garage but park it outside even in the winter as heat is a catalyst for rust. Below zero rust doesn't develop, cold hurts the bones as I get older but need to keep the bones on the GX intact.
Yeah I have a ph test kit for various reasons but at 50K knowing the coolant has never been changed don't care what the ph is time to change it. The plan right now is to keep mine until I kick the bucket so I'm a bit anal about maintenance. Working in the engine room of ships I'm used to PMS, planned maintenance system. I have a google docs named GX PMS and repair that I work from. Along with part numbers and intervals, it is 6 pages long now LOL.
Purchased with 40K on it and 2 years later almost 60K so ~10K a year. Works out perfect for oil changes in the Fall and Spring which is every 5K. Every 30K is fluid changes in pumpkins and transfer case. Coolant change at the same time with a tranny drain and fill.
At ~90K will do a borescope inspection for the valley plate leak. And change plugs & wires and at that time do a compression check on each cylinder. Also inspect for timing cover gasket leak and cam tower leak. Depending on the results then will make the decision to move forward or sell it. Hopefully will be keeping it, depending on inspection results. Then will replace:
Water pump
Radiator and hoses & clamps
Tranny cooler and hoses & clamps
TStat
Serpentine Belt
idler pulley
pulley tensioner
Alternator (Lux is higher rated than standard)
EGR Valve
Fan clutch
Suspension
Should get me another 90-100K although with time things like the AC will likely develop problems and little things will give out. But as long as I don't break down in the woods without cell phone reception they can be repaired.
The 460 is the best vehicle I have had in my life as far as comfort, lifestyle and meeting my needs. The 550 and 250 lack some of that luxury feel and moving to the LX is just a touch too large for the trails I run. The cost of an average new car right now is more than $50K something like the GX that I would want is much more than that. So still money ahead even after preventative maintenance cost.
I hope that rust monster stays the hell away from your rig for much more than a decade! Keep yer stick on the ice....