Fluid changes to do or not to do is the question. I am going to try and clear the mystery about when or if to change fluids. I know many are not going to agree with my ideas but then I am used to that.Engine Oil: At the max every 5000 miles or 90 days. If you put on a lot of highway miles you can extend this or if you do a lot of stop & go driving or idling then shorten it. Synthetic oil is a different set of requirements. Changing the filter and adding a quart every 5000 miles and a total change at 2nd or 3rd filter change. I can’t leave the oil in for that long it just doesn’t feel right, so I use regular oil. I do put synthetic in my wife’s car in the winter so it starts easier as it sits outside all day and it can get cold here. Power Steering Fluid: Anytime you do a repair IE pump, gear or hose. Do a complete change not just the reservoir. IF the fluid looks black change it. Transmission Fluid: Every 50,000 change the fluid and filter I am not a big fan of flushes but when you change the fluid change it all not just the converter. If you pull a trailer be sure you have a cooler and change it more often depending on how often you pull a trailer. Or anytime it looks bad or smells. When you change it check the pan for filings if there are sell the vehicle, or be prepared for a huge tranny repair bill. Constant transmissions are a whole new ball game. Pay strict attention to the owner’s manual nothing will destroy these transmissions like dirty fluid. From what I have seen they are going to be expensive to maintain.Brake fluid: Any time you do a break repair or have an ABS problem. If you don’t have ABS the repair change is not as important but I still recommend here again if you do it yourself it is cheap. I have cured many a ABS problem by changing fluid.Differential: Only if a repair is done or on a 4X4 I would recommend synthetic. Transfer Case: On older models only when repaired or dirty here again synthetic helps. On newer models with electronics check the owner’s manual and be sure to check the owner’s manual for correct fluid.Manual transmission: Only when repairing or if your owner’s manual calls for it. Be sure to use the correct fluid.Hints: If you have questions about the condition of PS or tranny fluid place a few drops on a white paper towel it will give a good indication of how dirty it is. When changing tranny or PS. Remove the return hose so you get all the fluid out. Add a can of additive; to the tranny and PS I use a half bottle in the PS. I prefer lube gard none other. Lube gard may make your fluid look black. Lucas makes a good product also but I don’t have a lot of experience except with the oil and that does an excellent job. Many of these jobs can be messy but you can save a considerable amount of money by doing them your self.Be certain you are using the right fluid if not you can do damsge.