aaronformella

This is a follow up with my previous post about transmission fluid fill levels I recently drove from Atascadero, CA to Bakersfield, CA, which is 120 miles, taking about 2 hours on mostly level terrain. I'm assuming this heated the transmission fluid to what could be considered a temperature achieved during prolonged driving conditions. I checked the fluid immediately after I arrived and the level was right at the bottom of the max fill line next to the "do not add" indication, which is great. So it seems that refilling with 5 quarts is safe to do as it will put your fluid level at the max fill line during prolonged driving and won't result in overfilling (which can damage the transmission) during prolonged driving. However, if I were frequently driving for long distances in mountainous terrain, I might add just a bit less (like 4.8 - 4.9 quarts) to keep the fluid from expanding past the max fill line in case it gets much hotter during such conditions. The user manual sort of addresses this when it mentions that you should have some fluid drained prior to using the car for towing, which would generate higher temps. As user "WWWPerA_ZN0W" posted immediatley above, apparently the brown color isn't necessarily an indicator that fluid needs replacement (it would actually depend on its 'degree of brownness'), but in my case, I didn't know if the fluid had ever been changed since I bought the car secondhand. The user manual indicates to change the automatic transmission fluid at 150,000 miles. However, I recently found out the hard way that as transmission fluid increases in mileage, it can cause 'varnishing' on the internal parts and reach a 'point of no return,' where, you're damned if you do or damned if you don't change the fluid. My understanding is that if you wait too long to change the fluid, the fluid performance decreases and transmission parts start to wear out more than they should, but the aged/high mileage fluid will 'fill in' worn areas in the transmission with a 'varnish' effect, keeping it working for a while, and that when new fluid is added, these areas are cleaned by the new fluid, resulting in the transmission no longer working properly when the fluid is changed. However, even if the old fluid is left in, eventually the transmission would fail that way too. I recently paid over $3k to have a CVT transmission replaced in a Nissan Cube when the fluid change interval was exceeded (by 60K btw). The transmission guy I talked to explained that it would probably be best to just leave the old fluid in, not change it, and just run it "into the ground." I got a second opinion from an auto tech that said changing the fluid, not flushing it, would probably be good to do. So, I decided to change the fluid (drain & refill). I should have listened to the transmission expert. The transmission problem immediately became worse and within a week the vehicle was inoperable and we had to replace the transmission. I'll admit this was a different situation however, with the 2009 Nissan Cube having a CVT transmission and the fluid change interval indicated as every 60,000 miles and it was only 'changed' at 30,000 miles when the transmission was initially replaced under warranty. The service was neglected thereafter until problems started to arise at 149,000 miles and then it was replaced again (unfortunately not under warranty). So now, I guess I would be a bit paranoid about waiting until 150,000 miles to replace the trans fluid in any vehicle and would much rather pay the ~$50 or less for new fluid and just do a drain and refill myself at half the recommended interval. In conclusion, keeping the transmission fluid fresh will do no harm, will help prevent future problems from aging/worn fluid, isn't expensive to do if you're doing it yourself, and even if you're paying someone else a couple hundred dollars to do it more frequently than recommended, it's much cheaper than fixing preventable problems. Here is a video that more thoroughly explains the 'varnishing' of a transmission

Thanks for all the info! Just wanted to share my experience so far with changing the transmission fluid in my 2012 Fusion SE 2.5L I4 with 6F35 automatic transmission. Here are some important takeaways listed at the top that might be helpful for novices like myself. Several things to note: - This vehicle takes about 5 qt of Mercon LV transmission fluid for a drain and refill procedure. - The lowest line on the dipstick (closest to the word hot) is reached at 4 qt refilled. The highest line is reached at about 5.25 qt refilled (measured when fluid is hot). - The fill level on the dipstick travels about 1/4 inch for each 1/2 quart added (so about 1/2 inch per 1 quart) (when fluid is hot). - "Hot" in this case is when the dashboard thermometer is at half way - Both underfilling and overfilling are harmful - The damn dipstick is finicky and hard to get an accurate reading with. Take a few measurements each time to make sure. - Follow the owner's manual procedure when measuring the fluid level with the dipstick. I tested this and if you don't, the fluid level will measure much higher (≈1/2 inch) than it does after performing the procedure of warming up the car, shifting through all the gears allowing them to engage for 10-15 seconds, putting it in park, and taking the measurement while the car is running. - Measure on a level surface. Obviously, don't make the mistake of using measurements taken while the car is on ramps. - If draining fluid while the car is on ramps, you will get about an extra 8 fl oz of fluid out if you drain on flat ground. If you started the procedure on ramps to have more working space, put the plug back in temporarily then finish draining on flat ground. - The 106 inch lbs or 12 Nm of torque for tightening the drain plug was way too light of force. My torque wrench (set to the equivalent 8.85 ft⋅lb) indicated that torque was reached before all the threads had even seated in completely. I just tightened the bolt down by feel until it seated firmly, then went about 1/8 turn more tight (≈ forearm tight with a 6" ratchet) which, seemed to be about how tight it was when I initially untightened it. - If you want to strain your fluid through a paper filter to look for metal debris, it will take a very long time; at least if using a paper coffee filter like I used. I drained the first quart through it and didn't see much so proceeded sans filter. More detailed information below: I recently bought the car used from a private seller with about 92k on it. My Fusion would occasionally have a delay in shifting into either 2nd or 3rd gear (6F35 automatic transmission). I took it to an auto tech friend for an inspection and he recommended a transmission fluid flush. The car now has 97k on it and the fluid is a light brown when spread out on a paper towel. The fluid appeared to be overfilled because it was showing way up into the "do not fill" section on the dipstick and it was very hard to get an accurate reading on the odd plastic design. This is where it was initially measuring when hot My dipstick is bent...I hope yours is too (somebody please tell me this is the way it's supposed to be) I was guessing this could be the cause of the shifting issue and figure it is good preventative maintenance to replace the fluid, especially not knowing the car's history. The plan was to use the procedure posted earlier in this thread (also referenced below) to 'flush' the transmission, but after procuring 12 qt of new fluid, I realized that this will not be enough so I settled for a single fluid change for now until I get more fluid (≈20 quarts are needed for this procedure, I didn't know at the time that the car will take 5 qts during a fluid change). An additional part of the plan was to measure the difference between the fluid level when hot vs cold, before draining, so I could figure out how much fluid to add later, since when adding fluid from the quart containers, it is at ambient ("cold") temperature and the fluid expands when heated. Several days before changing the fluid, I drained 1 qt to bring down the overfilled level with the plan of measuring the level again with the dipstick afterward to get an idea of what distance on the dipstick corresponds to what amount of fluid. I was surprised when I checked the level again and it was now well below the minimum fill line. I refilled with 1/2 qt and the line only went up a little way. I filled with another 1/4 qt and the fill level was just barely into the hashmarks. I don't know how to explain why the the dipstick level went down so far then didn't return to it's initial mark after most of the fluid was returned, but my best guess is that when the fluid level is near the maximum fill line at the end of the hashmarks, the surface tension of the fluid causes some capillary action and it is drawn up the letters of the 'do not add,' while some fluid leaks down from the wide section above and conjoins with the fluid below it when the dipstick is drawn out of the filler tube making it appear to be overfilled. Ughhh...Anyway, for some reason, I was not getting an accurate reading when I measured it initially several times before draining. One of the frustrating things is that the owner's and service manual instructions tell you carry out the procedures when the fluid is hot and the dipstick tells you to measure the level when hot, but I'd rather not have to figure out a way to preheat the new fluid to 185-200°F before adding it to get an accurate reading. The best way would be to get a cold reading on the dipstick, then measure the fluid drained when cold, then refill with that same amount when cold, making any adjustment according to the initial reading. The problem that prevented this was that I couldn't get an accurate dipstick reading initially as described previously. So, I settled for adding in a full 4 qt then driving to warm the fluid, bringing the temperature up to where the dashboard thermometer was at the half-way point, then going through the pre-measuring rituals from the owner's manual, then adding in more fluid, and repeating the process. It was very time consuming but I was finally getting accurate readings while knowing the fluid was around, "normal operating temperature," (185-200°F). I ended up placing in a full 5 qt with the dipstick measurement finally reaching about 3/4 the way up the hash marks (11 dots up the dipstick to be precise). The fill level on the dipstick travels about 1/4 inch for each 1/2 quart added (so about 1/2 inch per 1 quart). Below are some photos of the dipstick with marks corresponding to how many refilled quarts. dipstick level when 4 qt refilled was at bottom of minimum fill line dipstick level when 4.5 qt refilled was at 3 dots up the hashmarks dipstick level when 5 qt refilled was at 11 dots up the hashmarks Below are listed owner's and service manual procedures referenced above: Here is the 'flushing' procedure mentioned previously Here is what the owner's manual has to say about this specific 6F35 transmission (note: it lists different information for the manual transmission and AWF21 automatic transmission):

My guess is that the serpentine belt is putting a lot of force on the idler pulley and, with leverage, snapping the mounting bolt. I think all of the pulleys driven by the serpentine belt are in fixed positions with the exception of the belt tensioner pulley. This pulley moves on a spring-loaded lever or mechanism that allows it to be moved allowing the belt to be put in place by taking tension off and to take up the slack in the belt and put tension on it. The springs in the tensioner assembly can go bad. Maybe the tensioner isn't working properly and forces on the belt aren't being absorbed by the tensioner. I can imagine that in such a case, such forces could cause a weak link to snap; in this case the idler pulley bolt. The serpentine belt is driven by the crank-shaft pulley, that is driven by the engine's power, and the engine, being piston diven has peaks and lulls in output everytime it fires. These peaks cause vibration (quick changes in more tension and less tension) in the belt that are supposed to be dampened by springs in the tensioner. So if the tensioner isn't dampening these forces, maybe a weak bolt could be bent and relaxed over & over again (even if a small amount) enough to stress fracture the bolt (much like being able to break a metal coat hanger by bending it back and forth in the same spot repeatedly.) Just my theory...I would try and replace the serpentine belt tensioner assembly (not just the tensioner pulley). Can get em for $25- $30 on eBay and I hear they are not too difficult to replace yourself (YouTube it).