I see lots of discussion here about proper fluids and oils, and just wanted to offer my outlook. Granted, I come at this from the technician/shop side and not the DIY or consumer side, but here’s my point of view and a question:
If you came into the shop and saw me adding washer fluid to your transmission, you’d stop me. Why? Because it’s the wrong stuff! If I was adding brake fluid to the radiator you’d stop me, because it’s the wrong stuff. Yet time after time I see people recommending universal coolants or multi-vehicle transmission fluid or using one kind of motor oil in all three of their cars. I don’t get it. Here’s what we do at my shop:
If your owner’s manual, service information, and transmission dipstick all say your transmission uses Toyota Type T-IV, guess what? You’re car is getting actual T-IV, not a fluid that claims it meets T-IV requirements in addition to a number of other vehicles. If your engine requires dexos motor oil, that’s what your getting, not some house brand that claims it’s as good. If your cooling system requires Dexcool, you’re getting that, not green coolant or some universal blend. If the oil filler cap says 5W20, that’s what we’re putting in, not 5W30 because we think it’s ok in our climate. You get my point.
So my question is “why would you not use the correct and proper fluids and lubricants in your car?” Is there some perceived value in cost or convenience?
The difference in price between T-IV transmission fluid and plain old Dexron amounts to about $24 for a transmission service. The difference for a gallon of Dexcool over green coolant is $4/gallon. An oil change using dexos is $10 more than conventional oil.
Is saving $24 on a transmission service by using a questionable fluid really worth considering? Does anyone really insist on saving $4 on a gallon of coolant during a $400 radiator replacement?