Grumpy, I’m an AMSOIL guy. I do believe that their products are awesome, I’ve used them in many applications and always been happy with the results. I advocate for their products to friends and coworkers. I do think they’re superior. In the present case, this point is the reason for not using AMSOIL: AMSOIL doesn’t have DEX VI specific fluid - sure it may meet those reqs, but I agree with dvzzz and his statement regarding the one-for-all approach. The additives are really the differing factor. In an attempt to make the fluid better for most vehicles, I’d hope it doesn’t create a negative for the 6L80. Transmission fluid differs, as it should, depending on the components/product it interacts with. Truthfully, AMSOIL could be the BEST thing I could ever put in my transmission. But, I do want to be sure of it, I don’t want thousands lost to a transmission, and I don’t know how concrete AMSOIL’s warranty to that is. So for this time, I went with the Dex VI ACD. Next time, I may very well go AMSOIL. Given a longer timeframe, I may build confidence to the AMSOIL ATF. Also grumpy, I agree to the bullshit high heat of these 6L80s. Would you suggest a thermostat delete? I have gotten up to 230°F or so on occasion towing 10k through mountains...
So, went to drop off the truck this morning. Told the owner that although he mentioned using a Dex IV instead of AMSOIL, I didn’t have the time or motivation to go get any, so I have the AMSOIL. His face dropped and he said he would use it, but really doesn’t want me to be stuck with a transmission replacement bill, as he wouldn’t warranty the change himself if using AMSOIL. He said it seems like the finer compounds in AMSOIL’s ATF get into the electronics and cause failure/issues. I’m thinking this is the approach of my transmission guy. He knew a hell of a lot about the 6L80, and knows this industry VERY well. I think his grievance with AMSOIL is that although it may be Dex VI compliant, it’s not nearly the same. Also, my father who works on multi-million dollar mining trucks control modules referenced the insane amount of R&D he does for coatings and fluids near their control mods. The slightest change can reduce longevity exponentially. So, he is the one that suggested getting my own fluids, because I could probably get them for cheaper at retail, with deals going on. He expected me to bring my steak... but when I thought I was bringing prime rib, he told me it was an awful grade cut. ? Essentially this guy said he has had to replace a lot of the 6 speeds potentially due to AMSOIL, a lot of the 8 speeds because..... I think we all know their issues. And in the end, I’m going to be selling this AMSOIL, and I went with his ACDelco for $6.98/qt and he’s giving me a good deal on the change. All in all, the guy is VERY honest and I believe he is acting in my best interest. He’s a transmission guy and knows the products and outcomes well, I’m inclined to believe him. It’s not to say that for a different transmission, it’s not a great option. I also don’t know better, which is why I reached out here. For all those interested, though, this is what I did and why. Thanks for all the input!
I had purchased AMSOIL Signature Series ATF for my 18 Silverado - 6 speed. After having it sit for a while and never getting to a transmission flush on my own time, I called a local, honest, reputable transmission shop near me that has always treated my dad very well. They’re a no-bull, honest shop, and the owner is down to earth and knowledgeable regarding transmissions, as he should be. I informed him I had AMSOIL and wanted it switched with that, and he advised that for the 6L80E, it wasn’t a great idea. He has nothing against a better fluid, but he advised that AMSOIL doesn’t treat the electronics nicely, and it’s a common issue. I’m an AMSOIL guy, and do want him to use the AMSOIL fluid, but has anyone else heard of this or advise to simply use DEXRON VI and NOT AMSOIL?
K02s got put on about 2 months after the noticeable MPG drop. I run them at 40 psi- so although I’m sure there is more drag because of tread pattern/weight, it shouldn’t be awful. I will look into the brake clips as it’s a neat idea that has potential for cheap investment. I pretty much always get gas at the new Casey’s station in town (87). Just started experimenting with UNL88, too. If anything, I’ve seen no overall drop, if not a gain ? in MPG. I have AMSOIL fuel efficient 0w-20 oil, and their fuel efficient transmission fluid that I’ve heard great things about, to change out at the next OCI. Already switched both diffs and transfer case to AMSOIL. I will also be doing samplings prior to the change of both as a control comparison.
Good point, I failed to see that he had the wider 275s the first time. I’m rolling on stock sized BFG KO2s which are A) more aggressive and B) weigh 54% more (33lb->51lb) So, I get they are reducing efficiency some from stock. They are amazing tires, but if the price is 4mpg..... other options may quickly become more viable! Wish and hope that isn’t the case.
Interesting to see the difference with the Load Es. I can believe that they play a part of the drop, but especially in my case, with that being the only variable change, I really won’t believe it costs 4mpg. I’m going to spray my MAF sensor here soon and install the E2 catch can w/CSS. Maybe a difference, maybe not. Will probably get more invasive with an intake manifold and intake valve cleaning in a month or 2 when I’m closer to an oil change. I’d also like to buy a scope and scope my valves as well as my cats to see what shape they’re in. Such a fun time... ? Thanks for the help and any additional thoughts are appreciated! I’m guessing this will be an ongoing topic.
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Air filter (the cleanable, reusable K&N) has been clear. One of the first things I did when I got the truck was clean it out, reverse blow it, and ensure it wasn’t sapped with filter oil. But I suppose one thing I’ve not done is make sure the MAF sensor wasn’t already doused in the oil. Will be cleaning that ASAP. Any specific brand/product you recommend as a cleaner? As for scanning, not entirely handy on the ECM topic. I was looking at having a scan done as part of this process, but don’t know how exactly to go about it. Anything you recommend to do or a specific thing to ask of a mechanic? Very appreciative of the help.
Good insight. I’ve only owned the truck since March (the last 2000 miles), but a good buddy of mine bought it new at the end of 2018, and I’ve seen the hand-calculated mpg numbers since that time as to what his mpg was. He’s a lead foot and tows boats a lot and still averaged more than me in all circumstances, winter included. I’ve been trying to build up the best base I could, but time is in high demand as I move closer to a BBP time, intake, and muffler delete. But, I’d like hard numbers off the stock configuration so I’m then able to correct any problems before moving on to mods. Catch can is ready to be installed too- so if coked valves is it, I’d like them cleaned out and then a bottle of crc run through here and there after the catch can.
I realize that the AT KO2s (especially as aggressive as they are) will net lower mpg- but, I keep them at ~39-41 psi at any given time. I could also see the weight/aerodynamics of the topper reducing mpg. But these aside, the frustration is that it ISNT what it should be or has been. I know the truck is capable of 17-18mpg (as it used to be) especially how I drive it, but I’m not getting what I believe I should (and I think that’s a justified statement). I do appreciate your acknowledgement of other variables, but I’ve tried to minimize many of those already. Actually, much insight has come from reading YOUR posts on other threads! I’m really trying to find where to go next, as I think something is mechanically or digitally wrong. Coked intake valves? Catalytic converters acting up? I do use 87 unleaded and actually just started using 88 unleaded (E15) to see of any tangible difference. I would be down to run a test on 91 no ethanol (no 93 around here), but haven’t yet. As for a winter reference- I don’t believe that’s it... sure I could be wrong, but I’ve never seen a difference like this that could be relatable. Even then, should be better than 12-13mpg. I live in central IL so I’m sure winter fuel may still be out.
First off, I'll start by saying I know the MPG issue has always been beat to death. I'll also say that every conversation seems to lead to almost no real solution, rather people talking about how trucks don't get great MPG or maybe how someone should have a lighter foot or remove their leveling kit and heavier wheels. Now comes my situation (and I think that of others in the same boat). I have a 2018 Crew Cab Short Bed Silverado LT Z71 - 5.3L 6spd with the 3.42 gearing, right arounf 47,000 miles. Aside from bone stock, I have a cab-height topper and stock sized BFG KO2s. No lift/level, OEM exhaust, and OEM intake with a K/N performance filter. MPG used to be ~18 avg - right along with what one would expect and what most people get. Since last Fall (September 2019), I've been getting 12-13 city and 14-15 highway. I've also started logging all fuelups into fuelly for tracking. One point also worth noting: I drive like a grandpa: slow-moderate acceleration, try to stay in the 55-65 window as much as possible, and only go about 73 on the interstate. No matter what, the MPG still sucks. This is with minimal remote starts and idle time, using 55mph county roads instead of city/stoplights, etc. The purpose of this is to try to find a SOLUTION, or at least get pointed in the right direction for one. Many pages discuss MPG being low, but not WHY or HOW and that insight is what's most important. And another note: I didn't buy a truck to get 22 mpg. But, when your tank is 26 gallons and it should be putting you 450 miles, 350 is kind of a slap in the face. Simply put: it shouldn't be this way, so how can it be fixed. Any insight or personal experiences would be great. Only probable solution so far has been valve coking. This truck has almost all highway miles on it and I'm looking into Blackbear tuning, but I don't think that will be solving any underlying issues.
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