Hello all! New member here with my inaugural post. I've been an occasional lurker of these forums for some time, after having first stumbled across them some years ago while searching for the ideal oil to run in my vehicles when switching from conventional to synthetic. I come to you today with a specific oil-related scenario in which I could use the expertise of the collective hive mind. About a month ago, I picked up a 2002 Dodge Dakota SLT Club Cab 4x4 with the 4.7L V8 SOHC engine and 104,000 miles on the clock. Since purchase, I've done a lot of reading online in the course of researching DIY repairs for some of the mechanical imperfections I inherited from the previous owner. In the course of so doing, I've stumbled across many threads related to the dreaded oil sludging problem in the Dodge 4.7L V8's, often attributed to the smaller-than-normal oil drain passages in the block. I don't have any maintenance records from the previous owner(s) of my truck, but judging from the way various things have been cobbled together under the hood, it hasn't been maintained by the book. That said, the previous owner (who owned it for only 8 months) did recently perform an oil change with Mobil-1 5W-30 synthetic and some Lucas Oil Treatment, which has only a few hundred miles on it at this point and is still fairly clean. Partly because I'm a perfectionist and partly because I plan to use this truck somewhat heavily for business purposes, I wanted to find out what condition the engine internals were in and whether I have any sludge build-up or cause for concern regarding the oil pickup tube becoming clogged and starving the engine of oil, as has happened to many others. I read that one of the best and easiest ways to do this is to either remove the oil fill tube from the passenger side head or pull off a valve cover entirely. I therefore took a look down the oil fill tube the other day and could see a light, dried coating of sludge on its sides: After removing the oil fill tube from the passenger side cylinder head, I found quite a bit of soft goop at the entrance to the head and began to fear the worst: However, upon pulling the passenger side valve cover things didn't look quite as bad as I had thought â€” the only true "goop" was located at the entrance to the head from the oil fill tube. The cam and rockers have a light coating of varnish with concentrations of light sludge in nooks and crannies, but there's not much that you could pick up with, say, a Stanley screwdriver. Below are some photos: While the exposed topside of my passenger side cylinder head looks far better than many of the sludged 4.7L V8 engine photos that I've seen online, it also looks quite a bit dirtier than some others I've seen which are more or less spotless. I'm thinking I more or less managed to catch this engine before it managed to accrue too much sludge to make it possible to clean it all out. I did run a borescope down each of the oil return passages in the head, and all of them are currently clear with no signs of restriction. Sludge Removal Process This brings me to the second part of my question â€” I'd like to clean out my engine of any and all existing sludge as best as I can now so I have peace of mind. I usually run Pennzoil Ultra Platinum 5W-30 Synthetic oil and Fram Xtra Guard synthetic filters in all of my vehicles, and strictly manage change intervals by vehicle duty cycle. I feel good about my ability to prevent new sludge from forming if I can just start with a clean slate. I feel that now would be the perfect time to flush my engine, as the oil pan is rotting through and leaking anyway. I have plans to replace both it and the oil pump pickup tube, with the assumption that the screen on the oil pickup may be somewhat blocked. If my planned flushing were to disturb any hardened particles that would manage to stop up the oil pickup screen entirely, it shouldn't be a problem since I need to drop the pan anyway. If at all possible, I would like to clean out the engine as best I can before installing the new pickup tube and pan. I've done quite a bit of reading on the topic of cleaning agents, and have found a host of different products / solvents recommended: 1) Automotive Transmission Fluid â€” I've read many recommendations to add a quart or so of ATF prior to an oil change, then let the vehicle idle for an hour or so prior to draining the oil. However, I've also read that ATF can soften rubber seals and cause leaks and that Marvel Mystery Oil will work just as effectively while serving as a better lubricant, making it a somewhat safer option. If I do go this route, what type of ATF is recommended? 2) Auto-RX â€” Read lots of glowing reviews on this product here on the forums, with many claiming its cleaning performance is second to none. However, I've also read posts claiming that Auto-Rx has employed paid forum posters to shill for their product, that they've changed the formulation and patent four times in twelve years, and that the owner of the company is a real piece of work. On top of that it appears to be a slow-cleaning formulation â€” the instructions state that it works slowly over several oil changes. This makes this a questionable fit for my application as I'd like to clean out my engine now, but the truck currently isn't road worthy. 3) Diesel â€” I've seen #2 diesel recommended plenty of times to be used as a one-quart oil substitute an hour or so before an oil change, much like ATF. Some claim that diesel is what most "engine flush" products are based on, anyway. The upside here is the low cost on a per-oz. basis compared to other products, but this seems like it would be one of the more aggressive solvents with low lubricity that could possibly do some damage if you weren't extremely careful. 4) Kerosene â€” This is probably the second-most recommended product I've seen for cleaning out severe sludge immediately, second only to ATF. That said, the pros and cons seem to very closely mirror those of diesel. Low relative cost and immediate results, but low lubricity and the very real potential for engine damage if not used judiciously. 5) Marvel Mystery Oil â€” One of the most popular "snake-oil" additives for all types of things, MMO doesn't get rave reviews when it comes to sludge removal as it is a very mild cleaner. I get the feeling that it's more on the "protective lubricant" end of the spectrum as opposed to a cleaning solvent. That said, it's cheap at $3.88/quart and is recommended as being less harsh than ATF / Diesel / Kerosene and therefore lower risk. Likely won't provide immediate results, but will work slowly over time. 6) Pennzoil Ultra Platinum 5W-30 Synthetic Motor Oil â€” Pennzoil's Ultra Platinum is one of the most highly regarded synthetics, even more so than Mobil-1. Some say that it is so high in detergents that it is basically equivalent to an engine flush. It has significantly more detergents in it â€” Boron, in particular â€” than does Pennzoil's Platinum-grade synthetic, making it better at combating deposits. 7) Sea Foam Motor Treatment â€” Sea Foam is one of the most popular cleaners, with many stating they've obtained good results. However, others state that it's so thin that the cleaning agents likely dissolve quickly with engine heat. Another con is that the instructions indicate that it should be run at least 100 miles prior to an oil change for most effective results. It doesn't sound as if it works as immediately as ATF / Diesel / Kerosene. Final Thoughts Based on the above photos, how severe is the current sludge condition of the crankcase and valve train, and what product and process would you recommend for removing it? I am planning on tackling a fuel system and throttle body / combustion chamber cleaning separately, so this question is primarily intended to focus on solely the crankcase and valve train. Since I'm not positioned to actually drive my truck for hundreds / thousands of miles during the course of an engine cleaning, I'm leaning away from Auto-RX, Marvel Mystery Oil, and Sea Foam. The more immediate results of ATF / Diesel / Kerosene are more appealing, and since I can afford to stop the cleaning if need be to drop the pan and clean the pickup screen, that con of the more aggressive cleaners becomes less of an issue. I likely won't rely on Pennzoil Ultra Platinum alone for the initial cleaning, but will be running it as my motor oil of choice after the fact. It's also worth mentioning that I am currently performing a piston soak with Marvel Mystery Oil in an effort to free up some piston rings which I believe may be slightly sticking in the ring lands based on the results of a recent compression test. Once the 32 oz. of MMO has finished draining down past the rings into the crankcase, I could run the engine for awhile in an effort to see if it will perform any significant cleaning before draining it out. I would be very interested in hearing recommendations on not only which product you would use in my situation, but what ratio of cleaner-to-oil to use, how long to let the engine run during the cleaning, and at what intervals you would swap oil filters during the flush. Thanks in advance!