So here's the deal. I have an 05 LLY but the truck only has 25,000 miles (not a typo) I am in the process of doing some upgrades and was pondering the thought of changing out all fluids. Every service that has ever been done to this truck prior to my purchasing it, was done at the dealership. However I'm not sure if the tranny fluid, diff fluid, or any other fluids have been changed. All it said in the carfax when I purchased it was "oil changed, routine maintenance performed". That was once a year, roughly 1,800mi apart (that was the average milage driven per year) for the life of the truck.
So I want to know, should I bother changing out all the fluids considering that the truck is approaching 12 years old? If so which fluids should I change? I've already purchased Amsoil 15w40 for the oil change with the WIX filter, and already have a spin on tranny filter, just not sure what route to go with the rest of the fluids or if I should wait until the 50k mark. Any insight would be great.
GM dealers are notorious for putting DEX VI instead of the correct DEX III in the trans. I would replace the trans fluid with whatever you plan on using for the rest of the time. DEX VI will eventually cause the older Allisons to develop leaky seals (pre 2007, I think). If it were mine, I would also drain & flush the cooling system and replace with factory recommended Dexcool, unless it has a different coolant or you know it's been flushed and refilled. I would also recommend adding a lift pump for extra filtering and less strain on the CP3, especially if your location has mandated bio blends. If the turbo inlet hasn't been changed, I would do that before anything else is done, google LLY mouthpiece for info. LLYs have crappy injector connections and you would probably do well to search for "LLY icepick" trick. Also search "Duramax pump rub". Not trying to scare you, these are great trucks but like anything else, they have a few easily fixed quirks.
Yeah I've done a ton of research on all of this stuff as this is my second d-max so I already knew they all have their quirks. I stated that the truck is in the process of having some upgrades done, and here they are;
Full EGR delete with intake tube and up pipe, PCV reroute, turbo mouthpiece, CAI, Down pipe, DP back exhaust, pump rub kit from MA, rear diff cover, AD165, sulastics shackles and EFI Live by APT with edge insight for guages.
I just wasn't sure what to do as far as fluids. I've always been a Mobil guy but recently decided to try out Amsoil for the oil change and see if there is any noticeable difference. Is there anywhere I can find a full list of types of fluids and capacities for everything specifically for the LLY duramax? I used to have the list for my LB7 but I can't find it and I'm not sure if they're the same. I just want to make sure that I order enough of whatever it is I need. Thanks for the help guys
Personally, I would feel much better if I KNEW what the starting point was. Id change EVERY fluid if you can then you know where the truck is. Who knows how it was done before you.
Ok so I'm starting to see that I should change all the fluids? :wink2: I've already owned the truck for 2 years and all I've ever done is change the oil and oil filter and the fuel filter....truck runs great but should I be worried?
This may be a novice question but is there anywhere I can find a LLY specific fluids type and capacities chart? I know Amsoil has the different types and amounts but they have like 6 different rear ends listed etc... And I'm not sure which one I have.
Here's a list of what I'll look into flushing and replacing and what i already know, please feel free to add or correct me and to help fill in my blanks;
Engine oil and filter: Mobil 1 Delvac 15W40 (10 quarts)
Tranny oil and spin on: Mobil 1ATF (Allison) (? Quarts)
Rear diff: ???
Front diff: ???
Transfer case:???
Brake fluid: DOT3 (?quarts)
Coolant system: DexCool GM (?gallons)
Wow, so I completely missed that! And here's a rookie questions, how do I know which differential I have? There are multiple ring gears listed. I'm comfused'dunno;'dunno;
Not trying to make you worry but I've been having all sorts of problems with my low mile LB7. The couple of mechanics I've spoken too attribute it to lack of use. I bought it in 2011 with 37,000 miles and I'm at 65,000 now. Two sets of injectors and its in the shop now for a head gasket. Mechanic called me yesterday to tell me now the heads are bad and will need to replace them on top of the costly head gasket repair. He said there horribly corroded from electrolysis, probably from sitting with old radiator fluid in it. When I bought it the pink GM stuff was in there so I'm assuming it had the same fluid from 2003 until 2011. I've changed it 3x since then. I would change everything.
Not trying to worry you he says as I have a freaking coronary over here! :crying:
In all reality yes I will be changing out all fluids. Being that I've already had the truck for 2 years, something tells me I should've probably done this 2 years ago. Hopefully everything is still ok and I don't have any major issues.
You have the 11.5 Ring gear in the rear. Basically you need 2 qts for the front diff and 4 qts for the rear if it has a stock cover it it has an aftermarket diff cover it will take more depending on the brand of the cover.
Trans fluid should be changed out every two years with the stuff GM provides or every 4 years if you use something like Castrol Transynd which I get at the local Allison shop. There are many motor oils better than Amsoil and cheaper as well, including Pennzoil Long Life and Valvoline Premium Blue, both used by Ram dealers and Cummins in their engines. Both have better additive mixes than Amsoil. If you want to use a premium synthetic then get Valvoline Premium Blue or Red Line.
These trucks should have the front end greased every 3,000 miles and few owners actually do this. I would invest in a pistol grip grease gun with an angle adapter and start pumping.
Only weak point with the LLY engine was the early ones that were prone to head gasket failure. Something to watch for and check you oil if you start to consume coolant.
Thanks for the info. I do grease the front end any time the truck is up on a lift. I'm kind of beating myself up about not changing out these fluids earlier. I'm thinking about bringing the truck to a reputable shop around here (like limitless diesel) and having them look over the truck for me. I love the duramax platform and try to read and learn but I am far from an expert. So for piece of mind it may not be a bad idea to have knowledgeable guys take a look at it.
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