Major LMM Maintenance Questions

[Trm0002]

Alright, I've spent countless hours on this forum researching everything from dpf delete info to which type of oil is best suited for the Duramax engine, but I still have some questions:

1. Disregarding factory recommendations, what is a ballpark mileage for changing the diff. fluids, trans filter(spinoff), fuel filter? Any other fluid I left out?

2. My belt is making a whining/squeaking noise thats very nerve racking. It was bad last winter, went away or was faint this summer, and now is back. A guy at a oil change place said its just going to do that and I could put some kind of lubricant on it to quiet it, but the noise would return when it wore off. Another guy at a diff oil change place told me that if it's squeaking, it needs replacement. period.(he was very adamant about this) So what's the real truth to this?

3. Went to change my oil today and said I wanted to run a synthetic, the guy there says, "man, you don't want to do that. Its expensive, and GM doesn't recommend it in their diesel engines." I have never heard of that before, told them thanks for the information and left. Is this true and if so what's the major problems/ reasons for it?

4. What are the real facts about dino vs. synthetic oils? I'm talking change intervals, 'health' of the engine, mpg difference, everything. Note: This does not include AMS products. Every thread I've read has every statistic about their products ever recorded. No offense to you who run it, its just starting to sound a lot like a vacuum salesman. No offense.

The truck has 57000 miles on it. Fuel filter DIC says 64%. Never done any real heavy hauling. I'd like to keep the truck in good shape and I figured between 50-75k miles there would be some fairly major maintenance issues that would need my attention. I thought I would look here for info instead of asking anyone around where I live since people in the south tend to know everything about anything and are usually wrong. Thanks again for any help, sorry if I've stepped on anyones toes I wasn't intentionally trying to offend anyone. Everyone on here is very knowledgeable and very professional. And sorry this post is a mile and a half long.

Thanks and War Eagle!

[Buck]

1. use what the factory says and you will be fine...less is better but never more then what the owners manual says.

2. did you buy this truck new? Bother the dealer with crap like that. Don’t put belt dressing on there its bad for them imho.

3. that guys is a tool don't take your truck to "oil change places" to get anything done to it, its just asking for problems.

4. i use rottla t 5-40w full syn and have been since i got my first diesel 5 years ago. a corvette comes from the factory with full syn in it. the list gose on and on run syn if you can afford it and change your deno more if you can't.


welcome!

[dhaile]

Hello

ques 1 1-2 mpg increase with amsoil is my experience
ques 2 I do not have belt noise but in my past experience a good quality new belt resolve that problem.

ques 3/4 Advise from a lube guy is never that great. Corvettes and other gm vehicles come with synthetic fluid from factory. As long as you change it often, dino oil is great, synthetic offers longer life and better protection than most dino oils.

my 2 cents

[bigdaddydiesel]

WELCOME to the Neighborhood!!!

WOW, I have been called many things in the past but never a vacuum cleaner salesman... Man that is kind of harsh... Good luck finding what you need...

God Bless

Chris

[Trm0002]

Haha, I don't mean anything by it, I just read so many sales pitches on different threads I got kind of annoyed. Not to say anything bad about AMS or people who use it. One day I may be converted as well. I know it works wonders and is nice to not have to change the oil but once or twice a year, but I'm just not interested in it right now. Bigdaddy I'll contact you if I plan on switching to AMS, just won't be anytime in the immediate future.

I'm sure I sound like a very ignorant/lazy person getting my oil changed at shops instead of doing it myself. I live about 230 miles from home (in college) where drain pans, filter wrenches, etc would be, (it would be very wasteful to buy all that stuff all over again) and don't have time to go home (football games, and way too much studying). But I should make it to Thanksgiving to get everything done then. Probably should just break down, buy the stuff and do everything myself anyways, as the consequences of going there could cause major damage. It blew my mind when that guy said 'chevrolet doesn't recommend synthetic'. It didn't sound right when he said it..

[ChaseN]

i have had my 08 2 years this month and i rolled over 91k today.

the ONLY things i have done to it is oil & filter changes, tranny flushes, and check all the fluids. i've never had a problem out of the truck, other than i cannot get over 12-13mpg haha.

[Richard77]

5w 40 rotella T
Change spin on tranny filter every 5000

[DetTigerS09]

ya I think all cadillacs are shipped out with syn, synthetic is alot better for the engine and other major componets

[ChaseN]

Originally Posted by Richard77

Change spin on tranny filter every 5000

that's a bit much.
in the life of my 08 with 90k on it i've only changed it once myself and dealer has once.
no need for that often.

even with my 03 i had with 130k, i never changed it. dealer did once.

[Richard77]

chase have you changed the filter in the trans pan yet?