Yea, I have no idea how it's still working. I expected it to go away after the 30day trial, but it keeps working. Even the MyGMC.com page says I don't have a plan. The Basic Plan it mentions there doesn't show anything about the app working either.
@Grumpy Bear Thanks for a more complete picture of how viscosity works. Do you have a formula available for calculating film thickness vs viscosity at a given temperature? I'm certain it's not as simple as a single formula, but would be interesting to plot that data for given interfaces and see how the film thickness is affected. Also, any comments on the validity of putting an oil cooler inline with the filter? i was |..| that close to doing that on my TBSS in an attempt to keep the engine cool while towing with it. Thing blew a head gasket (probably due to previous owners rebuild capabilities), and I traded it away for my Sierra. Thought was to run a small trans fluid cooler in one of the brake ducts in the front fascia, and plumb that into an oil filter bypass fitting, and use a remote mount filter at the same time. Would have increased capacity slightly, and cooled the oil a bit along the way. The Sierra doesn't maintain nearly the high revs that the SS did, and it's a smaller engine overall, so I haven't been as worried about it, but am curious your take on the situation there. Thanks again!
Thanks for the addition. Good info.
Since I started this mess, guess I should chime in. There really hasn't been any technical information communicated aside from @Grumpy Bear 's post. That post (with good quantitative information), and a verbal conversation with a good friend that has had more AFM motors apart than he cares to admit gave me the confidence to run it like it is. I think @1SLOW1500 hasn't provided any qualitative reasoning for it being a bad idea, and is standing on his reputation at this point. @SierraHD17 called him on it, and well, he just leaned into the reputation instead of providing facts. Which is fine, everyone can evaluate it for what it's worth. I would like to see some good quantitative evidence of why it's a bad idea. Failed bearings, plugged lifters, overheated pistons, locked wrist pins, SOMETHING to say it's a colossally bad idea. I'm not taking it on a track day. My towing needs are over until spring. My warranty expired years ago. The risk of running the heavier oil was low enough that it didn't warrant another $70, and 90min of time to change out. We all have our level of comfort with risk, I'm OK with this one, clearly others are not. I'm going to risk it until a slightly earlier change at 90k miles (~3,500mi away at this point). I'll report back any findings when I drain it, or if the poo hits the fan before then.
Agreed. Lots of good info here, and I'm glad I stirred some discussion. Warranty isn't much if a concern at this point. Truck has 87.5k miles on it now. Factory warranty is long gone. The aftermarket warranty the dealership threw in for free has already proven to not be worth much more than the paper it's printed on. Supposedly it's got me covered to 150k, but they've already denied a whole laundry list of items that should have been otherwise covered IMO. Couple that with a royally shitty dealership experience every time I go in, and I've resigned myself to doing my own work moving forward on this vehicle. I drove it the 250ish miles here, and will most likely leave the heavier oil in for the near future. Might change at 3k instead of 5k this time though. I'll report back on how it fares. Thanks again to all who replies, and for keeping it civil and informational. I appreciate the efforts!
Thanks for the detailed analysis. This is the info I really wanted to find, but couldn't in short order this morning or last night. That's exactly what I did. Didn't have to change it this morning, and the consensus when I left was that it was fine. Drove it 300mi this morning, pressure is a litter higher but otherwise no I'll effects that I can tell. Probably swap it out a bit earlier than normal, but will otherwise run it this way for awhile. Thanks to all who replied.
Just changed the oil in my '15 Sierra 5.3. Oil spec is 0W-20 per manual and fill cap. Realized I was using 5W-30 as I was pouring in the 8th quart. I've read of the DoD lifters having problems. How sensitive are they to pressure changes from oil viscosity? Do I need to change before a 600mi road trip tomorrow, or am I good to go? Gut tells me it's no big deal, head tells me that 0W-20 was spec'd for a reason and I shouldn't mess with that. Anyone have any thoughts?
Word of mouth with experienced use it always the best bet. Glad you got some good data there. My buddy with the KO2's that complained about wet traction has moved to the Wildpeak AT3W's and loves them. He's in a Jeep Cherokee (old boxy one, not new Fiat based one) for reference.
Nope still running the 5100's. They look nice, but my Ranchos rode almost exactly the same. I suspect the crap heavy KO2's are more unsprung weight than any of the shocks are designed to deal with. Coupled with running a relatively low profile size, on overly stiff sidewalls has lead to my rough riding truck. Seriously it rides like a damn half broken hay wagon with no suspension at all. Which sucks for a $50k luxury pickup, especially when compared with the other competition in this segment. Currently I'm waiting on the KO2's to wear out so I can swap back to a lighter less stiff tire and see how that works out. Until I just keep my dentist on retainer to put the teeth back in my head every so often from the rough ride.
This is a legit question, and a hard one to answer. For me, I've got some personal experience at this point and a good friend that had similar reports. Those are corroborated with others here. I'm unsure how TireRack rates their tires. Are they from users, or are they from "new tire tests" against some baseline metric? Hard to say. The KO2 traction in the mud, overall toughness, and look is superior. The remainder of the driving dynamics are not. Weight, stiffness, sound, and wet traction are all poor. IMO, unless you NEED the superior toughness the 10-ply sidewall provides (It doesn't add squat to towing capability IMO since almost all P-Rated tires in this size range will overload the axle before the tire), there are better All Terrain tires available. With that said, I drank the "Bilstien 5100's are the best shocks ever" Kool-Aid, and am sadly disappointed in those. Best advice I can give on this front.......The KO2's are REALLY popular tires. I would ask around to anyone in your area that you see at a gas station, grocery store, etc that has them and see what they say. Use in your market will be the best info you can get.
Correct. They blow goats for dollars in the rain. So much so that I won't let the wife drive the truck in the rain, and I won't drive it without AWD (Auto 4wd) engaged. The rear slides out entirely too easy, unplanned 4-wheel drifts on freeway onramps, and general lack of braking traction. Retrieving our boat in the summer requires 4wd if the ramp is even a little wet. They SUCK in the rain/wet. I have about 50k miles on them now. They were "not great" when new, and they have progressively gotten worse over time. The grip like a scared cat on carpet in the dry, as well as in the mud. They're tough as nails off road in rocks and "heavy" gravel. A light drizzle is a white knuckle drive. They're also ridiculously heavy, and absurdly loud. if I spent more than ~50% of my time off road, they would be a go to tire. Since I'm closer to 80-90% ON road, they don't work for me.
I'm curious about this as well. Currently running a 275/55/20, considering a 275/60/20. Not a huge jump by any measure, but just a shade more sidewall and height for clearing ruts. Noticed last week while cleaning that the bottom of my running boards have some significant scuffing on them. Guessing they're just off the ground on a well traveled farm path I frequent.
Thanks for the great feedback. I appreciate the review. I'm like 99% certain these will be my next tires. I'm completely over the harsh ride, loud noise, and lack of wet traction of the KO2's. They might be great tires, but they're clearly just not for me.
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